<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE article  PUBLIC "-//NLM//DTD Journal Publishing DTD v3.0 20080202//EN" "http://dtd.nlm.nih.gov/publishing/3.0/journalpublishing3.dtd"><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" dtd-version="3.0" xml:lang="en" article-type="research article"><front><journal-meta><journal-id journal-id-type="publisher-id">TEL</journal-id><journal-title-group><journal-title>Theoretical Economics Letters</journal-title></journal-title-group><issn pub-type="epub">2162-2078</issn><publisher><publisher-name>Scientific Research Publishing</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="doi">10.4236/tel.2015.53043</article-id><article-id pub-id-type="publisher-id">TEL-56556</article-id><article-categories><subj-group subj-group-type="heading"><subject>Articles</subject></subj-group><subj-group subj-group-type="Discipline-v2"><subject>Business&amp;Economics</subject></subj-group></article-categories><title-group><article-title>
 
 
  Spatial Competition between Health Care Providers: Effects of Standardization
 
</article-title></title-group><contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>jörn</surname><given-names>A. Kuchinke</given-names></name><xref ref-type="aff" rid="aff1"><sup>1</sup></xref></contrib><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Jürgen</surname><given-names>Zerth</given-names></name><xref ref-type="aff" rid="aff2"><sup>2</sup></xref></contrib></contrib-group><aff id="aff2"><addr-line>Wilhelm Loehe University for Applied Science Fuerth, Fuerth, Germany</addr-line></aff><aff id="aff1"><addr-line>Bauhaus University, Weimar, Germany</addr-line></aff><pub-date pub-type="epub"><day>08</day><month>05</month><year>2015</year></pub-date><volume>05</volume><issue>03</issue><fpage>375</fpage><lpage>388</lpage><history><date date-type="received"><day>4</day>	<month>April</month>	<year>2015</year></date><date date-type="rev-recd"><day>accepted</day>	<month>18</month>	<year>May</year>	</date><date date-type="accepted"><day>22</day>	<month>May</month>	<year>2015</year></date></history><permissions><copyright-statement>&#169; Copyright  2014 by authors and Scientific Research Publishing Inc. </copyright-statement><copyright-year>2014</copyright-year><license><license-p>This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/</license-p></license></permissions><abstract><p>
 
 
  In the international health care literature the impacts of competition in health care markets are discussed widely. But aspects of standardization in regional health care markets with no price competition received comparatively little attention. We use a typical Hotelling framework to analyze a regional health care market with two health care providers competing in (vertical) quality after the scope of medical treatment has been set (horizontal quality). We conclude that in the basic model both health care providers will use vertical quality to separate from each other. In the next step we introduce a standard in vertical quality of which one health care provider
  —
  the standard profiteer—could better cope with. In the standardization case a more homogeneous supply can be expected and there is a higher possibility that the standard follower has to leave the regional health care market. Therefore standardization of health care quality could strengthen monopolistic tendencies.
 
</p></abstract><kwd-group><kwd>Hospital Competition</kwd><kwd> Hotelling Model</kwd><kwd> Quality Competition</kwd></kwd-group></article-meta></front><body><sec id="s1"><title>1. Introduction</title><p>The perspective of industrial economics has been rarely applied to the health care sector (see, for example, Dranove and Satterthwaite [<xref ref-type="bibr" rid="scirp.56556-ref1">1</xref>] ; Gaynor and Vogt [<xref ref-type="bibr" rid="scirp.56556-ref2">2</xref>] ). Many publications focus on empirical analysis; only very few try to elaborate explicit microeconomic model (cf. Gal-Or [<xref ref-type="bibr" rid="scirp.56556-ref3">3</xref>] ). Regarding theoretical approaches, many authors employ the idea to discuss horizontal competition (cf. Dranove and Satterthwaite [<xref ref-type="bibr" rid="scirp.56556-ref1">1</xref>] ; Gaynor and Haas-Wilson [<xref ref-type="bibr" rid="scirp.56556-ref4">4</xref>] ; Pauly [<xref ref-type="bibr" rid="scirp.56556-ref5">5</xref>] ). Limited attention has been paid to standardization effects and horizontal competition within a regional health care market. Nevertheless, in many health care systems there is a tendency to enforce standardization in inpatient as well as outpatient care. As this has direct impacts on the competition environment within a regional health care market, these effects are modeled in this paper. We want to outline competition between two health care providers which face regulated prices and can only differentiate by means of quality competition. Moreover, as cost payers require quality improvements in health care supply, all health care providers have to optimize their way of organizing health. One strategy for them is to standardize production procedures, especially regarding surgery but the magnitude of the relationship seems not really clear (cf. Weitz et al. [<xref ref-type="bibr" rid="scirp.56556-ref6">6</xref>] ). Hence, our paper captures the idea of quality differences by focusing on quality competition in regional health care environments (cf. Brekke, Nuscheler and Straume [<xref ref-type="bibr" rid="scirp.56556-ref7">7</xref>] ). In consequence, we develop an expanded Hotelling model in two steps: we analyze quality choice using an expanded Hotelling framework. There are several methods for analyzing markets for differentiated products. Following Shy [<xref ref-type="bibr" rid="scirp.56556-ref8">8</xref>] , we can find non-address approaches as well as models that employ location ideas (pp. 143 ff.). We employ a Hotelling framework for describing the regional health care market, because hospital competition combines product heterogeneity and different patient preferences. We allow the providers to choose their location, their scope of treatments and the quality of treatments being offered. The hospital supply faces a line of consumers who have different preferences for one health care provider. But there are also some patients at the fringe that could be attracted by the means of quality competition. In the following we use the term horizontal quality when we focus on the choice of location and scope of treatments.<sup>1</sup> This is the first stage of our model. On the second stage, the hospital chooses vertical quality. Vertical quality describes the way how one given treatment is produced. This means vertical quality depends for instance on minimum further education standards for physicians or minimum levels for medical devices and pharmaceuticals etc. By means of backward induction, vertical quality can be explained endogenously by the level of horizontal quality that the health care provider chooses first. We introduce standardization, e.g., a standard of vertical quality for treatments in the regional health care market. The standard could be the result of a benchmark process initiated by the regulator or a cost payer (insurance company). This means, we assume that a third party is able to observe the vertical qualities and to prescribe the higher quality as a standard. The regulator sets a level of vertical quality for both health care providers, which is binding for both. For analytical reasons we assume that level of vertical quality set by the regulator corresponds to the first-best level set by provider 1. In this case provider optimizes his profit function. Hence, health care provider 1 can better cope with the standard whereas health care provider 2 has to converge to quality level of his competitor. In consequence, we can show the interaction between the two possibilities of quality setting contingent on a quality leadership in the market. On one hand there are areas for substitution; on the other hand, comparing the own-cost and the cross-cost effects, the standard follower has to consider limitations on the substitution incentive. The paper is organized as follows: Section 2 describes the typical characteristics of a regional health care market. Section 3 introduces the basic model of spatial competition. The model is expanded in Section 3.2 to include a standardization process in the regional health care market. Section 4 summarizes our findings and outlines their implications for further research.</p></sec><sec id="s2"><title>2. Quality Competition in Spatial Health Care Markets</title><p>For the discussion it is necessary to define the conditions and restrictions outpatient (physicians) and inpatient (hospitals) health care providers face within the typical health care markets. In a typical patient-physician-situa- tion, patient’s primary demand is directed to a physician who diagnoses the patient and makes the first treatment decisions. For more severe illnesses the patient will be transferred to a higher equipped health care provider for appropriate care. This can be an outpatient specialist or a hospital. For the sake of simplicity we assume that the patient is free to choose between health care providers, i.e., we do not differentiate between inpatient and outpatient care. But patients are typically heterogeneous when considering the scope and the location of health care supply. Hence, a regional health care market simultaneously encompasses heterogeneity in demand as well as in supply. Moreover, in contrast to other markets, prices in health care markets are regularly set by a regulator or the third payer (insurance).<sup>2</sup> This strengthens the relevance of competition in quality. In the tradition of industrial economics, we distinguish between vertical quality and horizontal quality. Patients’ preferences for vertical quality are uniformly ranked, i.e., all patients prefer a higher vertical quality when all prices are fixed. Consequently, all patients are better off when the level of medical quality which health care provider 1 offers rises.<sup>3 </sup>Horizontal quality refers to characteristics where the optimal choice depends on the characteristics of the consumer. Health care provider location or the range of treatments offered can be represented through the horizontal quality variable. Patients who are closer to health care provider 1 have less opportunity costs when choosing provider 1 than those located closer to provider 2. In contrast to a rise in vertical quality a rise in horizontal quality does not necessarily constitute a Pareto improvement. Consumers, whose optimal horizontal quality was close to the offered horizontal quality before the change, may face a decline in utility as the deviation between their desired quality and the quality offered increases (cf. Shy [<xref ref-type="bibr" rid="scirp.56556-ref8">8</xref>] ). For the purpose of this paper we regard that the chosen horizontal quality is necessarily fixed for the time being. Therefore, the only remaining choice concerns vertical quality.</p></sec><sec id="s3"><title>3. Model of Quality Competition</title><sec id="s3_1"><title>3.1. Basic Model</title><p>A simple model of a regional health care market can be derived from the papers of Glazer and McGuire [<xref ref-type="bibr" rid="scirp.56556-ref9">9</xref>] , Montefiori [<xref ref-type="bibr" rid="scirp.56556-ref10">10</xref>] or Brekke et al. [<xref ref-type="bibr" rid="scirp.56556-ref11">11</xref>] . Considering the results of Gravelle [<xref ref-type="bibr" rid="scirp.56556-ref12">12</xref>] and Calem and Rizzo [<xref ref-type="bibr" rid="scirp.56556-ref13">13</xref>] we use the approach of the spatial competition literature to model the effects of standardization. This should provide a good intuition for the probable consequences of the implementation of a new form of standardized care. Brekke, Nuscheler and Straume [<xref ref-type="bibr" rid="scirp.56556-ref7">7</xref>] develop a specific model that combines ideas of spatial competition in the tradition of Hotelling [<xref ref-type="bibr" rid="scirp.56556-ref14">14</xref>] with quality competition. This is our point of reference in this paper.<sup>4</sup> Like them we employ a two-stage model of health care provision with fixed prices. In the first stage, each health care provider decides on horizontal quality. He selects his range of treatments offered. <sup>5</sup>After the decision on horizontal quality at the first stage the health care providers compete by choosing the quality of care they provide in the second stage, i.e., by choosing a level of vertical quality.</p><sec id="s3_1_1"><title>3.1.1. Demand for Health Care</title><p>As a first step we model patients’ demand for health care. We follow Hotelling’s idea of a linear city<sup>6</sup> and assume rational consumers with perfect and complete information about all relevant parameters. The termai denotes the absolute position of the health care provider I on the [0, 1] interval.<sup>7</sup> We assume health care provider 1 is located left within the spectrum and health care provider 2 is located right <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x8.png" xlink:type="simple"/></inline-formula> and<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x9.png" xlink:type="simple"/></inline-formula>. Hence, we assume there is a perceivable horizontal quality difference so that patient’s location or need for a specific treatment will generally direct them to one of the providers, i.e., the average patient is not indifferent between health care providers but has a decided preference for one. Demand for a (specific) unit of health care hl is assumed to be independently identically distributed on the [0; 1] interval. In the line of a linear model the patients are heterogeneous considering the both health care providers which resembles some baseline preference for proximity of care.<sup>8</sup> In addition to horizontal quality we consider vertical quality in the standard of care for any given treatment, which is described by the parameter<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x10.png" xlink:type="simple"/></inline-formula>. The variable costs for crossing the distance to a regional provider are borne by the patient. They are assumed to be constant and denoted by t. As we have noted before, within the model<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x11.png" xlink:type="simple"/></inline-formula>, the price for medical treatment, is independent of the scope of medical treatment and the vertical quality offered. Now, we additionally assume <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x12.png" xlink:type="simple"/></inline-formula> is regulated and fix for all health care providers.<sup>9</sup> Similar to Brekke, Nuscheler and Straume [<xref ref-type="bibr" rid="scirp.56556-ref7">7</xref>] each patient faces the following objective:</p><disp-formula id="scirp.56556-formula1308"><label>(3.1)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x13.png"  xlink:type="simple"/></disp-formula><p>The patient of interest is the indifferent one located at the margin between the both health care providers. He has to decide whether health care provider 1 or health care provider 2 are entitled to treat him.<sup>10</sup> We assume, that net utility is always positive, even for the lowest vertical quality possible. The whole market is always covered for the regulated price <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x14.png" xlink:type="simple"/></inline-formula> which is equal for all patients. Each consumer demands one unit of the good and a second unit does not offer additional utility. The indifferent patient can be described with the following location <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x15.png" xlink:type="simple"/></inline-formula> which is the solution to:</p><disp-formula id="scirp.56556-formula1309"><label>(3.2)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x16.png"  xlink:type="simple"/></disp-formula><p>The result allows us to denote the position h in the linear city. Both health care providers face the same indifferent patient. Consequently, health care provider’s demand <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x17.png" xlink:type="simple"/></inline-formula> is the fraction of the market just up to the marginal consumer<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x18.png" xlink:type="simple"/></inline-formula>.</p><disp-formula id="scirp.56556-formula1310"><label>(3.3)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x19.png"  xlink:type="simple"/></disp-formula><p>For the other health care provider <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x20.png" xlink:type="simple"/></inline-formula> holds. For the non-spatial case there is an intuitive interpretation of this variable. If <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x21.png" xlink:type="simple"/></inline-formula> is high, a substantial part of patients choose health care providers offering a wide range of treatments. If <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x22.png" xlink:type="simple"/></inline-formula> is low, the majority prefers treatment by providers with a lower degree of horizontal quality<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x23.png" xlink:type="simple"/></inline-formula>, i.e., by providers who specialize in a small number of treatments. We split expression (3.3) into three parts:<sup>11</sup></p><disp-formula id="scirp.56556-formula1311"><label>(3.4)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x24.png"  xlink:type="simple"/></disp-formula><p>The position of<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x25.png" xlink:type="simple"/></inline-formula>, the marginal consumer, depends on vertical quality difference, the degree of competition and average horizontal quality. We are particularly interested in the degree of competition. From the second term over braces we infer that the degree of competition rises when t is low and/or the gap between <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x25.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x26.png" xlink:type="simple"/></inline-formula> and <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x25.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x26.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x27.png" xlink:type="simple"/></inline-formula> is small, i.e. there is little differentiation in horizontal quality.</p></sec><sec id="s3_1_2"><title>3.1.2. Supply of Health Care</title><p>Taking health care provider 1 as our representative producer in a world with two health care providers, we get the following profit function:</p><disp-formula id="scirp.56556-formula1312"><label>(3.5)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x28.png"  xlink:type="simple"/></disp-formula><disp-formula id="scirp.56556-formula1313"><graphic  xlink:href="http://html.scirp.org/file/3-1500719x29.png"  xlink:type="simple"/></disp-formula><p><sup>10</sup>The model is limited to selective medical treatments a patient can anticipate and plan.</p><p><sup>11</sup>Cf. Pf&#228;hler and Wiese [<xref ref-type="bibr" rid="scirp.56556-ref17">17</xref>] : 244.</p><p><sup>12</sup>The case where this condition is not met presents us with an argument against insufficiently high reimbursements, as these could lead to low levels of quality and a sub-optimally narrow range of treatments. Interested readers are referred to Newhouse [<xref ref-type="bibr" rid="scirp.56556-ref18">18</xref>] and Pope [<xref ref-type="bibr" rid="scirp.56556-ref19">19</xref>] .</p><p><sup>13<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x30.png" xlink:type="simple"/></inline-formula></sup>. See Brekke, Nuscheler and Straume [<xref ref-type="bibr" rid="scirp.56556-ref7">7</xref>] : 212.</p><p>We set <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x31.png" xlink:type="simple"/></inline-formula> for the regulated price all health care suppliers face. We suppose that reimbursements cover costs, i.e. that <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x31.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x32.png" xlink:type="simple"/></inline-formula> is valid. If reimbursements do not cover costs there will be no voluntary supply, consequently, this case is irrelevant in a market economy.<sup>12</sup></p><p>The parameter <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x33.png" xlink:type="simple"/></inline-formula> signifies the variable cost of a treatment while <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x33.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x34.png" xlink:type="simple"/></inline-formula> denotes fixed cost. The variable costs occur if the minimum level of quality <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x33.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x34.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x35.png" xlink:type="simple"/></inline-formula> is provided. The costs <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x33.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x34.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x35.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x36.png" xlink:type="simple"/></inline-formula> for producing higher vertical quality <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x33.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x34.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x35.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x36.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x37.png" xlink:type="simple"/></inline-formula> are supposed to be convex.<sup>13</sup> Costs for a given level of vertical quality are therefore a combination of the variable costs for the provision of basic quality and a higher vertical quality cost increment.</p><p>There are already a few very straightforward results to be derived from this profit function. Profit can only be positive, if reimbursements exceed variable costs <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x38.png" xlink:type="simple"/></inline-formula> and rises with the difference between these two variables. Variable cost for vertical quality <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x38.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x39.png" xlink:type="simple"/></inline-formula> and fixed costs <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x38.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x39.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x40.png" xlink:type="simple"/></inline-formula> have a negative impact on profits. These results are general and do not depend on the specifications of the model. Substituting the results derived in (3.3) into the profit function we get:</p><disp-formula id="scirp.56556-formula1314"><label>(3.6)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x41.png"  xlink:type="simple"/></disp-formula><p>Now we analyze the effects of decisions on vertical and horizontal quality. We know, that provider 1 has a smaller <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x42.png" xlink:type="simple"/></inline-formula> than provider 2, therefore the first term within the brackets can only be positive if<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x42.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x43.png" xlink:type="simple"/></inline-formula>. Provider 1, the provider with the smaller range of treatments offered in the non-spatial interpretation, has an incentive to offer higher vertical quality, because this increases his profits. If he offers a lower vertical quality the difference in horizontal quality between providers will lower his profits compared to the case in which both providers offer homogenous goods. For this vertical quality distribution, profits for a provider with the higher vertical quality rise, the smaller the difference in horizontal quality <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x42.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x43.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x44.png" xlink:type="simple"/></inline-formula> and the smaller transport costs t are. Consequently, there is an incentive to diversify horizontally for this provider.</p></sec><sec id="s3_1_3"><title>3.1.3. Optimal Vertical Quality</title><p>In our basic model we assume that both health care providers offer different levels of vertical quality. The first order condition for the profit-maximizing quality <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x45.png" xlink:type="simple"/></inline-formula> is:</p><disp-formula id="scirp.56556-formula1315"><label>(3.7)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x46.png"  xlink:type="simple"/></disp-formula><disp-formula id="scirp.56556-formula1316"><graphic  xlink:href="http://html.scirp.org/file/3-1500719x47.png"  xlink:type="simple"/></disp-formula><p><sup>14</sup>The second-order condition is negative<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x48.png" xlink:type="simple"/></inline-formula>.</p><p><sup>15</sup>For the discussion of health care provider 2 cf. Appendix A.1.</p><p>As we have assumed that <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x49.png" xlink:type="simple"/></inline-formula> the above equation only holds if<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x49.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x50.png" xlink:type="simple"/></inline-formula>. Otherwise the first order condition for a profit-maximum would not be satisfied, as<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x49.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x50.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x51.png" xlink:type="simple"/></inline-formula>. Profit-maximizing vertical quality<sup>14</sup> can be written as:</p><disp-formula id="scirp.56556-formula1317"><label>(3.8)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x52.png"  xlink:type="simple"/></disp-formula><p>Comparative static for optimal quality yield for<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x53.png" xlink:type="simple"/></inline-formula>:<sup>15</sup></p><disp-formula id="scirp.56556-formula1318"><label>(3.9)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x54.png"  xlink:type="simple"/></disp-formula><p>This equation tells us, that a higher level of horizontal quality (<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x55.png" xlink:type="simple"/></inline-formula>rises) induces the level of competition. Hence, the health care provider is compelled to increase the vertical quality<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x55.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x56.png" xlink:type="simple"/></inline-formula>. The implication of this relationship can be explained looking at the differences in heterogeneity of medical supply.</p><p>Comparing this result with the impact of <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x57.png" xlink:type="simple"/></inline-formula> gives:</p><disp-formula id="scirp.56556-formula1319"><label>(3.10)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x58.png"  xlink:type="simple"/></disp-formula><p>An increase in the (horizontal quality) distance between the two health care providers decreases provider 1’s incentive to offer a high level of vertical quality.</p><disp-formula id="scirp.56556-formula1320"><label>(3.11)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x59.png"  xlink:type="simple"/></disp-formula><p>The incentive to provide quality is negatively related to t, the parameter denoting transport cost or the cost of quality mismatch for patients. This is plausible, as competition from other health care providers is lower when opportunity costs (the product of the actual distance/quality mismatch and the cost parameter) are high. The health care provider can anticipate that the patient will compare higher transport costs with a potential loss of vertical quality.</p><disp-formula id="scirp.56556-formula1321"><label>(3.12)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x60.png"  xlink:type="simple"/></disp-formula><p>As <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x61.png" xlink:type="simple"/></inline-formula> is true per definition, the impact of an increase in <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x61.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x62.png" xlink:type="simple"/></inline-formula> is to lower the level of vertical quality. Costs directly reduce profit and consequently reduce the incentive to compete via higher quality.</p><disp-formula id="scirp.56556-formula1322"><label>(3.13)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x63.png"  xlink:type="simple"/></disp-formula><p>The above equation shows that the negative relationship between costs and quality is not only true for the cost of treatment, but also for the costs of quality improvements<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x64.png" xlink:type="simple"/></inline-formula>. Again, a reduction of profits lowers the incentive to compete for them via higher vertical quality.</p><p>Result 1</p><p>The conclusions for both health care providers are (compare A.1):</p><p>・ It exists a partial substitution between horizontal and vertical quality. If one health care provider sets its medical supply more homogeneously in comparison to the other health care provider, he has to increase vertical quality in order to cope with the higher level of competition (3.9).</p><p>・ If health care provider 2 changes horizontal quality, e.g., both providers gets more heterogeneous, health care provider 1 has less incentive to increase vertical quality (3.10).</p><p>・ Higher opportunity costs reduce the patients’ gain from higher vertical quality. In consequence the provider has to differentiate and expand its vertical quality supply (3.11).</p><p>・ Higher costs for producing health care <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x65.png" xlink:type="simple"/></inline-formula> reduces the possibility for provider 1 to increase his vertical quality (3.12).</p><p>・ Higher costs of vertical quality <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x66.png" xlink:type="simple"/></inline-formula> will directly reduce the interest of provider 1 to increase the vertical quality (3.13).</p></sec><sec id="s3_1_4"><title>3.1.4. Optimal Horizontal Quality</title><p>When determining optimal horizontal quality <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x67.png" xlink:type="simple"/></inline-formula> for each health care provider, we have to keep in mind that <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x67.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x68.png" xlink:type="simple"/></inline-formula> is true per definition. In other words, for provider 1 an increase in <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x67.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x68.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x69.png" xlink:type="simple"/></inline-formula> would reduce differentiation between providers, whereas an increase in <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x67.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x68.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x69.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x70.png" xlink:type="simple"/></inline-formula> would c.p. induce a greater distance. Backwards induction stipulates both health care providers to choose an optimal level of <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x67.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x68.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x69.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x70.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x71.png" xlink:type="simple"/></inline-formula> when determining optimal horizontal quality<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x67.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x68.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x69.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x70.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x71.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x72.png" xlink:type="simple"/></inline-formula>. Inserting <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x67.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x68.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x69.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x70.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x71.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x72.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x73.png" xlink:type="simple"/></inline-formula> into Equation (3.6) gives us the new profit function:</p><disp-formula id="scirp.56556-formula1323"><label>(3.14)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x74.png"  xlink:type="simple"/></disp-formula><p>The implicit optimal value of <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x75.png" xlink:type="simple"/></inline-formula> considering the first order condition is:</p><disp-formula id="scirp.56556-formula1324"><label>(3.15)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x76.png"  xlink:type="simple"/></disp-formula><p>The optimal value of <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x78.png" xlink:type="simple"/></inline-formula> and <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x78.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x79.png" xlink:type="simple"/></inline-formula> cannot be computed directly. Hence, for both health care provider sexist a kind of reaction function for the optimal values<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x78.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x79.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x80.png" xlink:type="simple"/></inline-formula>:<sup>16</sup></p><disp-formula id="scirp.56556-formula1325"><label>(3.16)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x81.png"  xlink:type="simple"/></disp-formula><p>Considering health care provider 1 we observe that the second derivative of (3.14) over <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x82.png" xlink:type="simple"/></inline-formula> is also negative which means that there is a local profit optimum at the left side of the range<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x82.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x83.png" xlink:type="simple"/></inline-formula>.<sup>17</sup></p><p>In consequence both reaction functions resemble “strategic complements”. Hence, it is possible that there is a corner solution possible for both health care providers. Using the Equation (A.10) we can differentiate between two relevant cases considering the assumption about the relation between <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x84.png" xlink:type="simple"/></inline-formula> and<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x84.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x85.png" xlink:type="simple"/></inline-formula>. Looking at the marginal</p><p>differentiation of both profit functions we have to discuss <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x86.png" xlink:type="simple"/></inline-formula> and<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x86.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x87.png" xlink:type="simple"/></inline-formula>.<sup>18</sup></p><p>・ The sign of <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x88.png" xlink:type="simple"/></inline-formula> will be negative as long as <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x88.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x89.png" xlink:type="simple"/></inline-formula> holds. Hence, for provider 1 <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x88.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x89.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x90.png" xlink:type="simple"/></inline-formula> follows.</p><p>・ But for the reverse cost relation it is also possible that provider 1 would choose<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x91.png" xlink:type="simple"/></inline-formula>.</p><p>・ Considering <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x92.png" xlink:type="simple"/></inline-formula> for provider 2, using equation A-13 it is possible that <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x92.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x93.png" xlink:type="simple"/></inline-formula> is valid.</p><p>・ In consequence, assuming <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x94.png" xlink:type="simple"/></inline-formula> it may be possible that for both providers a kind of a “Nash-equilibrium”</p><p>exists that induces <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x95.png" xlink:type="simple"/></inline-formula> and<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x95.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x96.png" xlink:type="simple"/></inline-formula>.</p><p>For the sake of simplification we set <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x98.png" xlink:type="simple"/></inline-formula> henceforward and we only discuss the partly marginal effects for the reaction function of health care provider 1.</p><p>As we cannot directly infer the marginal effects for the first stage, we use the optimal level of <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x99.png" xlink:type="simple"/></inline-formula> and the marginal effects (stage two).<sup>19</sup> Following the first-order condition for vertical quality, we compare the results for both health care providers at the second stage:</p><p><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x100.png" xlink:type="simple"/></inline-formula>for health care provider 1 (3.17)</p><p><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x101.png" xlink:type="simple"/></inline-formula>for health care provider 2</p><p>For <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x102.png" xlink:type="simple"/></inline-formula> and assuming <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x102.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x103.png" xlink:type="simple"/></inline-formula> holds the following must be true:</p><disp-formula id="scirp.56556-formula1326"><label>(3.18)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x104.png"  xlink:type="simple"/></disp-formula><p>・ If <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x105.png" xlink:type="simple"/></inline-formula></p><p>・ and <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x106.png" xlink:type="simple"/></inline-formula></p><p>Under the described circumstances competition will always result in a higher vertical quality for the health care provider 1 with the lower<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x107.png" xlink:type="simple"/></inline-formula>. This sheds light on the conditions that could be relevant for different qualities <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x107.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x108.png" xlink:type="simple"/></inline-formula> if horizontal quality is set. Therefore, the decision for the horizontal quality at stage one is taken in view of the capabilities for producing vertical quality.</p><p>The influence of the variable costs <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x109.png" xlink:type="simple"/></inline-formula> can be described as follows:</p><disp-formula id="scirp.56556-formula1327"><label>(3.19)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x110.png"  xlink:type="simple"/></disp-formula><p>The sign of the fraction is not directly clear. Hence, we use the following assumption to get an idea of the re-</p><p>lationship between horizontal and vertical quality. The denominator will be positive <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x111.png" xlink:type="simple"/></inline-formula></p><p>・ If: <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x112.png" xlink:type="simple"/></inline-formula></p><p>・ or: <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x113.png" xlink:type="simple"/></inline-formula></p><p>In this case a high level of a reimbursement <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x114.png" xlink:type="simple"/></inline-formula> makes the second, fourth and sixth term of the numerator</p><p>negative. Nevertheless, the whole numerator is positive as long as<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x115.png" xlink:type="simple"/></inline-formula>. In consequence <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x115.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x116.png" xlink:type="simple"/></inline-formula> could</p><p>be assumed.</p><p>For a change in quality costs ϕ1 the following holds:</p><disp-formula id="scirp.56556-formula1328"><label>(3.20)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x117.png"  xlink:type="simple"/></disp-formula><p>The sign of the denominator is still assumed to be positive, as we have outlined above. Hence, following the</p><p>basic assumption <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x118.png" xlink:type="simple"/></inline-formula> the whole fraction gets negative and <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x118.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x119.png" xlink:type="simple"/></inline-formula> holds.</p><p>When we look at the parameter t we get:</p><disp-formula id="scirp.56556-formula1329"><label>(3.21)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x120.png"  xlink:type="simple"/></disp-formula><p>For the denominator the impact of the assumption concerning quality cost will be helpful, too. The numerator</p><p>will be negative for the range <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x121.png" xlink:type="simple"/></inline-formula> Hence, the result could be<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x121.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x122.png" xlink:type="simple"/></inline-formula>. The more <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x121.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x122.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x123.png" xlink:type="simple"/></inline-formula> converges to</p><p><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x124.png" xlink:type="simple"/></inline-formula>the more probable the expected result <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x124.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x125.png" xlink:type="simple"/></inline-formula> gets.</p><p>Result 2</p><p>We could summarize our findings:</p><p>・ An increase of the costs <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x126.png" xlink:type="simple"/></inline-formula> will induce health care provider 1 to reduce his horizontal quality. Additionally, both health care providers will be incited to reduce their vertical quality (3.19).</p><p>・ Higher costs <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x127.png" xlink:type="simple"/></inline-formula> will incite health care provider 1 to expand his horizontal quality. Only when health care provider 1 has a large cost advantage in <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x127.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x128.png" xlink:type="simple"/></inline-formula> he would accept to converge to the other health care provider. Referring to the optimal value of <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x127.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x128.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x129.png" xlink:type="simple"/></inline-formula> higher costs <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x127.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x128.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x129.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x130.png" xlink:type="simple"/></inline-formula> will directly reduce the health care providers’ incentive to increase vertical quality (3.20).</p><p>・ An increase in opportunity costs t will incite health care provider 1 to reduce his horizontal quality, i.e., to decrease the differentiation. Only if health care provider 1 has an advantage <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x131.png" xlink:type="simple"/></inline-formula> it could be optimal to expand horizontal quality a<sub>1</sub> and reduce differentiation (3.21).</p></sec></sec><sec id="s3_2"><title>3.2. Standardization and the Impact on Competition</title><sec id="s3_2_1"><title>3.2.1. Preliminaries</title><disp-formula id="scirp.56556-formula1330"><graphic  xlink:href="http://html.scirp.org/file/3-1500719x132.png"  xlink:type="simple"/></disp-formula><p><sup>20</sup>We do not analyze the welfare maximizing level of<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x133.png" xlink:type="simple"/></inline-formula>.</p><p><sup>21</sup>This result may directly be followed by the assumption<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x134.png" xlink:type="simple"/></inline-formula>.</p><p>Up to now we have discussed the case where both health care providers could differentiate between horizontal and vertical quality. Now we introduce the idea of a standard for vertical quality. We assume that both health care providers are not able to anticipate this step by the regulator. They are not able to form expectations about the timing, process or nature of the actual regulation and are therefore not able to choose their competition parameters strategically. This is not entirely implausible as things can change quickly in health care systems. For the purpose of this model we assume that the regulator chooses the highest observable level of vertical quality as standard. In the following we continue to set that <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x135.png" xlink:type="simple"/></inline-formula> holds and therefore assuming all other things equal health care provider 1 has an advantage in vertical quality<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x135.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x136.png" xlink:type="simple"/></inline-formula>.<sup>20</sup></p><p>Now, our assumption is that the regulator may set a vertical quality <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x137.png" xlink:type="simple"/></inline-formula> that would perfectly match the optimal quality<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x137.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x138.png" xlink:type="simple"/></inline-formula>.<sup>21</sup> However, for the health care provider this choice is at random. As the United Kingdom, Germany and Switzerland require their independent health care providers to document their quality levels, the assumption of an in&#173;formed regulator is plausible. As a consequence, both health care providers have to accept this standardized level of vertical quality but health care provider 1 could cope better than health care provider 2.</p><p>Following the regulation rule, health care provider 2 has to accept the level <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x139.png" xlink:type="simple"/></inline-formula> and provide a sub- optimal level of quality from his point of view. The position of the indifferent patient changes to h<sub>Standard</sub>:</p><disp-formula id="scirp.56556-formula1331"><label>(3.22)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x140.png"  xlink:type="simple"/></disp-formula><p>Both health care providers choose the levels of <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x141.png" xlink:type="simple"/></inline-formula> and <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x141.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x142.png" xlink:type="simple"/></inline-formula> within the model. Moreover, as the vertical quality is not a relevant parameter for competition anymore, health care provider 1 would benefit from the given standard. Hence, he will be the standard profiteer because his horizontal quality fits the standard vertical quality. The new profit function for health care provider 1 can be written as:</p><disp-formula id="scirp.56556-formula1332"><label>(3.23)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x143.png"  xlink:type="simple"/></disp-formula><p>Considering the first order condition the following holds:</p><disp-formula id="scirp.56556-formula1333"><label>(3.24)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x144.png"  xlink:type="simple"/></disp-formula><p>As we assume that the standard follows <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x145.png" xlink:type="simple"/></inline-formula> the health care provider 1 will optimize <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x145.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x146.png" xlink:type="simple"/></inline-formula> contingent on his expectations about the optimal level<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x145.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x146.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x147.png" xlink:type="simple"/></inline-formula>.</p></sec><sec id="s3_2_2"><title>3.2.2. Impact of Regulation on Health Care Provider 1</title><p>After the description of the standard we want to elaborate the impact of standardization upon competition in horizontal quality. For the optimal horizontal quality of the standard profiteer <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x148.png" xlink:type="simple"/></inline-formula> we apply the total differentiation of the first order condition and insert the marginal effects from the second stage. With other words, we assume the optimal level of vertical quality for the standard profiteer and then look at standardization. As there is no possibility to substitute a difference in horizontal quality with vertical quality, we have to discuss the optimal in a one stage model. Hence, both health care providers have only to consider the distance between each other as a level of competition. As we cannot derive a mutual best answer for each health care provider we concentrate on discussing the marginal effects for both health care providers: For the impact of <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x148.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x149.png" xlink:type="simple"/></inline-formula> on <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x148.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x149.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x150.png" xlink:type="simple"/></inline-formula> the following holds:</p><disp-formula id="scirp.56556-formula1334"><label>(3.25)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x151.png"  xlink:type="simple"/></disp-formula><p>and</p><disp-formula id="scirp.56556-formula1335"><label>(3.26)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x152.png"  xlink:type="simple"/></disp-formula><p>Considering Equation (3.25) the own-cost effect may be ambiguous. As the denominator is always positive the overall sign depends on the numerator. The second term will be positive as long as the second addend in the brackets exceeds the first addend, i.e., for high levels of<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x153.png" xlink:type="simple"/></inline-formula>. With low levels of <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x153.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x154.png" xlink:type="simple"/></inline-formula> the second term of (3.25) is negative and therefore the standard profiteer has a direct incentive to increase horizontal quality. Consequently, a relatively small remuneration reduces the standard profiteer’s incentive to attract more patients through an increase in horizontal quality. From (3.26) we can directly conclude that there is no relevant impact on the costs of the competitor. Considering the parameter <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x153.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x154.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x155.png" xlink:type="simple"/></inline-formula> we get:</p><disp-formula id="scirp.56556-formula1336"><label>(3.27)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x156.png"  xlink:type="simple"/></disp-formula><p>and</p><disp-formula id="scirp.56556-formula1337"><label>(3.28)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x157.png"  xlink:type="simple"/></disp-formula><disp-formula id="scirp.56556-formula1338"><graphic  xlink:href="http://html.scirp.org/file/3-1500719x158.png"  xlink:type="simple"/></disp-formula><p><sup>22</sup>The following only holds as long as<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x159.png" xlink:type="simple"/></inline-formula>.</p><p>The expression will always be positive if the basic assumption <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x160.png" xlink:type="simple"/></inline-formula> is still valid. Higher costs for the provision of vertical quality increases the incentive to diminish horizontal differentiation.<sup>22</sup> For the parameter t we get:</p><disp-formula id="scirp.56556-formula1339"><label>(3.29)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x161.png"  xlink:type="simple"/></disp-formula><p>The expression will be always positive, if the basic assumptions are still valid. Higher travelling or quality mismatch costs reduce the standard profiteer’s incentive to differentiate horizontally.</p><p>Result 3</p><p>As the health care provider could directly benefit from the vertical standard his decision on horizontal quality could be characterized as follows:</p><p>・ Higher costs of c<sub>1</sub> will incentivize the standard profiteer to increase horizontal quality differentiation (a<sub>1</sub>↓). But this effect could be outweighed by higher reimbursement <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x162.png" xlink:type="simple"/></inline-formula> (3.25). The standard profiteer has not to consider the costs of the other health care provider (3.26).</p><p>・ If the costs for the standardized vertical quality rise the standard profiteer will reduce the difference in horizontal quality and increase the degree of competition (3.27). The standard profiteer has only to bear the own-cost effects (3.28).</p><p>・ If patients have to bear higher opportunity costs for selecting one health care provider the standard profiteer will also reduce the difference in horizontal quality and increases the degree of competition (3.29).</p></sec><sec id="s3_2_3"><title>3.2.3. Impact of Regulation on Health Care Provider 2</title><p>The next equations show the impact of vertical quality regulation on health care provider 2’s decision for horizontal quality. He has to cope with the vertical standard <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x163.png" xlink:type="simple"/></inline-formula> and therefore we want to elaborate<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x163.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x164.png" xlink:type="simple"/></inline-formula>. Although both providers must accept the standard health care provider 2 is like a “follower” in typical oligopolistic models. Due to regulated vertical quality, competition can only take place through a choice of locations or differences in the scope of treatments. For the standard follower there is c.p. a high incentive to hold the distance in horizontal quality. For the standard profiteer the opposite seems to be true. We can discuss these effects by using the marginal effects for the standard follower: For the production costs <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x163.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x164.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x165.png" xlink:type="simple"/></inline-formula> we get:</p><disp-formula id="scirp.56556-formula1340"><label>(3.30)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x166.png"  xlink:type="simple"/></disp-formula><p>The sign is definitely negative as long as the basic assumption <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x167.png" xlink:type="simple"/></inline-formula> holds. The impact of <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x167.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x168.png" xlink:type="simple"/></inline-formula> on <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x167.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x168.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x169.png" xlink:type="simple"/></inline-formula> is unambiguous. As we assumed, the standard follower has to bear higher vertical quality costs<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x167.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x168.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x169.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x170.png" xlink:type="simple"/></inline-formula>. If there is a rise in the cost for basic health services<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x167.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x168.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x169.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x170.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x171.png" xlink:type="simple"/></inline-formula>, the follower has an incentive to reduce the distance to the standard follower.</p><p>The standard follower has also to anticipate the cross-cost-effects:</p><disp-formula id="scirp.56556-formula1341"><label>(3.31)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x172.png"  xlink:type="simple"/></disp-formula><p>As denominator and numerator are negative by assumption the overall effect is always negative. The standard follower has also to reduce the horizontal quality given the provider’s 1 costs for producing health increase. For a change in <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x173.png" xlink:type="simple"/></inline-formula> the following is valid:</p><disp-formula id="scirp.56556-formula1342"><label>(3.32)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x174.png"  xlink:type="simple"/></disp-formula><p>The sign of the numerator is positive due to the basic assumption<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x175.png" xlink:type="simple"/></inline-formula>. Higher costs for producing vertical quality additionally diminish health care provider 2’s profits, and therefore his incentive to attract patients. Instead of increasing the level of competition, he chooses a greater horizontal differentiation from the standard profiteer to reach the point where his marginal quality costs equal marginal returns. But he also has to consider the cross-cost effect:</p><disp-formula id="scirp.56556-formula1343"><label>(3.33)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x176.png"  xlink:type="simple"/></disp-formula><p>In consequence of our basic assumption the effect will be always negative. Hence, the standard follower is compelled to reduce horizontal differentiation if the exogeneous standard costs which fit better for health care provider 1 increase. When we look at t we get:</p><disp-formula id="scirp.56556-formula1344"><label>(3.34)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x177.png"  xlink:type="simple"/></disp-formula><p>The impact seems to be clear. The numerator is definitely negative, whereas the denominator is always positive. A higher cost parameter t also encourages the standard follower to reduce his horizontal quality.</p><p>Result 4</p><p>The standard follower reduces most of his parameters for competing in spatial competition:</p><p>・ The own-cost effect is always positive. The standard follower will try to reduce the degree of competition because of its worse cost situation in comparison to the standard profiteer (3.30). But he has also to anticipate the cross-cost effects, which are opposite to the own-cost effects (3.31).</p><p>・ A similar result could be inferred by discussing the costs for the standardized vertical quality<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x178.png" xlink:type="simple"/></inline-formula>. As the own-cost effect is positive which would incite the standard follower to reduce the degree of competition (3.32) the cross-cost effect is negative (3.33).</p><p>・ For higher opportunity costs the standard follower will react similar to the standard profiteer and reduce the horizontal differentiation (3.34).</p></sec></sec></sec><sec id="s4"><title>4. Conclusions and Outlook</title><p>We use an extension of a Hotelling model to analyze the impact of a standardization of vertical quality on horizontal quality in a regional health care market. In the basic model both health care providers compete in horizontal and vertical quality. The basic model tells us that the choice of vertical quality <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x179.png" xlink:type="simple"/></inline-formula> will be made conditionally on optimal horizontal quality <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x179.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x180.png" xlink:type="simple"/></inline-formula> of the competitor. The success of competing in vertical quality is directly dependent on the comparison of the cost parameters <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x179.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x180.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x181.png" xlink:type="simple"/></inline-formula> of both competitors. In the standardization case the standard profiteer gets similar results like in the basic model. But, the standard follower fairly loses control over horizontal quality because he has to cope with the suboptimal vertical standard, which he has to anticipate in his decision for horizontal quality. This leads to a non-optimal level of vertical quality as well as horizontal quality for the standard follower. Considering the impact of own-cost effect and cross-cost effect, some direct implications for regional competition exist:</p><p>・ The follower is driven out of the market, because he is not able to offer the standard quality as the costs of doing so are prohibitively high for him;</p><p>・ or he has to accept the chosen quality which is (more) beneficial for the standard profiteer and has to accept lower profits in comparison to the non-standard case.</p><p>As we can directly infer from the comparison of basic model and standardization model, there is substitution between horizontal and vertical quality, which may be beneficial for health care providers as well as for patients if the standard leader can outweigh vertical quality with horizontal quality. More investigation in this area is necessary especially when discussing the impacts on welfare. We focus on a restricted area of horizontal quality where both health care providers are free to choose. For further research it would be interesting to widen our approach by incorporating a more detailed discussion on the scope and level of standardization. Moreover, it could be beneficial to widen the analysis to another form of standardization where both health providers could anticipate and probably influence the standard setting.</p></sec><sec id="s5"><title>Appendix</title>A.1. Vertical Quality<p>The second health care provider has to optimize the following profit function:</p><disp-formula id="scirp.56556-formula1345"><label>(A.1)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x182.png"  xlink:type="simple"/></disp-formula><p>The first order condition for the profit maximizing quality <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x183.png" xlink:type="simple"/></inline-formula> is:</p><disp-formula id="scirp.56556-formula1346"><label>(A.2)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x184.png"  xlink:type="simple"/></disp-formula><p>The optimal level of <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x185.png" xlink:type="simple"/></inline-formula> is:</p><disp-formula id="scirp.56556-formula1347"><label>(A.3)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x186.png"  xlink:type="simple"/></disp-formula><p>Using comparative statics we get:</p><disp-formula id="scirp.56556-formula1348"><label>(A.4)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x187.png"  xlink:type="simple"/></disp-formula><disp-formula id="scirp.56556-formula1349"><label>(A.5)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x188.png"  xlink:type="simple"/></disp-formula><disp-formula id="scirp.56556-formula1350"><label>(A.6)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x189.png"  xlink:type="simple"/></disp-formula><disp-formula id="scirp.56556-formula1351"><label>(A.7)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x190.png"  xlink:type="simple"/></disp-formula><disp-formula id="scirp.56556-formula1352"><label>(A.8)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x191.png"  xlink:type="simple"/></disp-formula><disp-formula id="scirp.56556-formula1353"><label>(A.9)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x192.png"  xlink:type="simple"/></disp-formula>A.2. Horizontal Quality<p>For the optimal horizontal quality we insert the optimal values <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x193.png" xlink:type="simple"/></inline-formula> and <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x193.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x194.png" xlink:type="simple"/></inline-formula> into the profit function (3.14) und compute in an explicit manner. Because we are looking at a corner solution we get:</p><disp-formula id="scirp.56556-formula1354"><label>(A.10)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x195.png"  xlink:type="simple"/></disp-formula><p>The whole expression will be negative if the second addend cannot compensate the negative impact of the</p><p>first addend. If there is no difference in vertical quality the expression simplifies to:<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x196.png" xlink:type="simple"/></inline-formula>.</p><p>Considering the second derivation, we get:</p><disp-formula id="scirp.56556-formula1355"><label>(A.11)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x197.png"  xlink:type="simple"/></disp-formula><p>As the first addend will always be negative and the expression within the brackets encompasses positive as well as negative parts we can assume that the whole formula get negative, as long as the assumption for the first derivative holds. The result for the optimal choice of <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x198.png" xlink:type="simple"/></inline-formula> given <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x198.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x199.png" xlink:type="simple"/></inline-formula> can be computed by inserting the optimal values <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x198.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x199.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x200.png" xlink:type="simple"/></inline-formula> and <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x198.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x199.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x200.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x201.png" xlink:type="simple"/></inline-formula> into the profit function (3.14) (cf. (A.10)):</p><disp-formula id="scirp.56556-formula1356"><label>(A.12)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x202.png"  xlink:type="simple"/></disp-formula><p>As we can see from (A.12) the optimal level of <inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x203.png" xlink:type="simple"/></inline-formula> depends on<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x203.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x204.png" xlink:type="simple"/></inline-formula>, the other provider’s horizontal quality. We are looking at a reaction function<inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x203.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x204.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="http://html.scirp.org/file/3-1500719x205.png" xlink:type="simple"/></inline-formula>. The corresponding reaction function for health care provider 2 is:</p><disp-formula id="scirp.56556-formula1357"><label>(A.13)</label><graphic position="anchor" xlink:href="http://html.scirp.org/file/3-1500719x206.png"  xlink:type="simple"/></disp-formula></sec><sec id="s6"><title>NOTES</title></sec></body><back><ref-list><title>References</title><ref id="scirp.56556-ref1"><label>1</label><mixed-citation publication-type="other" xlink:type="simple">Dranove, D. and Satterthwaite, M. (2000) The Industrial Organization of Health Care Markets. 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