Table 2 and Figure 2 show the statistics and relationship between the number of confirmed cases and the passenger traffic volume in each province. Accordingly, the flow of population and the number of confirmed diagnoses have a moderately strong, approximately linear, positive correlation. Although Guangdong locates far from Hubei, it is one of the most developed provinces in China, with advanced transportation center at the mouth of the Pearl River and the largest seaport in southern China. Guangdong ranked top one in its passenger traffic volume (1,421,440 million people) in 2018. This results in Guangdong becoming a susceptible region to contagious diseases. Especially during the Spring Festival, the massive flow of population led to interaction and exchange between suspected cases and the public, resulting in the high confirmed cases in Guangdong.

Figure 3 illustrates the correlation between average temperature of January and February and confirmed cases in each province/municipality/autonomous region. Accordingly, there is no relationship between confirmed cases and the temperature warmer than 0 degrees Celsius. For regions that are colder than 0 degrees Celsius, the low temperature is accompanied with low diagnoses. Besides Heilongjiang (an anomalous case), none of the provinces/municipalities/autonomous regions with negative temperatures have more than 400 confirmed cases. Although the novel coronavirus prefers colder environment, temperature appears to be a secondary influencing factor of 2019-nCoV transmission. According to the data in Table 3, Guangdong’s temperature ranked the top two among China. Based on the relationships illustrated in the scatterplot, Guangdong turns out to have a higher number of confirmed cases.

Figure 4 illustrates the correlation between the number of medium- and large-sized households and the accumulated confirmed cases in each province/municipality/autonomous region in China mainland by 19th February 2020. There is a moderately strong, positive, approximately linear correlation. Since members within each household have close contact with each other every day, the larger families, the higher the possibility for infectious people to transmit 2019-nCoV to a broader group. Table 4 shows the statistics of medium- and large-sized households in each province. There are 17,860 million families that have more than two members in Guangdong. In this case, it is prone for Guangdong to have a greater scope of disease-spreading than other provinces.

Figure 5 indicates the correlation between the number of urbanized population and confirmed cases. As implied in the scatterplot, there is a moderately strong, positive, approximately linear correlation between the two variables. Urbanized population displays a more concentrated residential distribution compared to rural population. A denser distribution of people is linked with increased contacts between individuals, resulting in a higher risk of contagion. Guangdong has 80,220 million households that live in urban areas, ranking the first. This correlates to Guangdong’s 1332 cases of diagnosis, as shown in Table 5.

Figure 6 indicates, at the very beginning stage of coronavirus outbreak, a significant rate of increase in Guangdong compared to the other three provinces examined in this paper. This shows that Guangdong’s government and the public lacked serious awareness for disease control, which causes a large amount of confirmed diagnosis in later stages (in February).

Tianjin is located at the Bohai Bay in the Great Plains of North China. It has the

largest seaport and water and land transportation facilities in northern China. Nevertheless, transportation at Tianjin is mainly constituted of maritime shipping and transporting activities with less population flow, as indicated above in Table 2. Therefore, Tianjin has successfully controlled the spread of disease.

Tianjin locates in the Beijing-Tianjin-Hebei region, the northern part of China. The average temperature during January and February in Tianjin is −2.4 degrees Celsius. With a lower-than-0-degrees-Celsius temperature, Tianjin has fewer cases of confirmed 2019-nCoV.

During the disease outbreak, Tianjin has carried out “Implementation measures during coronavirus disease outbreak for promoting economic and social development” early in time. As illustrated in Figure 7, at the very beginning stage, Tianjin has a slow rate of increase in confirmed cases per day. Additionally, the Jinyun application has shared detailed trip information of diagnosed patients to inform residents about ongoing situations efficiently. As indicated in Figure 8, Tianjin has the lowest number of diagnoses within the Beijing-Tianjin-Hebei region: the confirmed cases in Beijing and Hebei province are about 3 to 4 times of those in Tianjin. This underscores that the government control through on-time policy-making and the update of detailed patients’ information has been especially critical for disease prevention and control.

According to Table 2, the population traffic volume of Guizhou is 930,250 million people in 2018, ranking in the top ten. However, during the outbreak, the heavy snow forced Guizhou to close roads and airport runways, which dissuades population movement and reduces the spread of disease.

Guizhou is mainly constituted of mountainous, located at the Yungui Plateau. This reduces population density and concentration. In light of Table 4 and Table 5, Guizhou Province has only 6820 million urbanized households and 5080 million large households. The geography of Guizhou results in less urbanized residential concentrations and more scattered city arrangement across the provinces. Thus, the coronavirus cannot spread out easily.

Guizhou province has carried out five pieces of implementation measures to strengthen disease control: first, identify suspected cases from data; second, verify their detailed profile; third, acquire their daily routine and mobility information; fourth, strictly ask for following report of their condition; fifth, restricted suspected cases from inflowing into Guizhou [9]. According to a detailed news report in Beijing Evening News, Guizhou has security officers collecting information about individuals’ mobility and body temperature [10]. In addition, Guizhou has subsidized small and medium-sized enterprises to ensure their steady development during work extension. The high government awareness is conducive to disease control.

Though according to Table 2, the passenger traffic volume is 315,680 million people in Heilongjiang, ranking low, its Northern location makes Heilongjiang prone to infection. Trips to Heilongjiang are longer than those to other provinces, which increases the potential exposure to the virus and suspected cases. This further increases the possibility of infection, resulting in more confirmed cases in Heilongjiang.

Heilongjiang is located in the very northern part of China with an average outdoor temperature of −17.9 degree Celsius during January and February. The freezing weather dissuades people from room ventilations. Especially when people congregated, the indoor and enclosed areas make disease-spreading easier, causing a significant increase in diagnosis.

Heilongjiang’s policies and control are not so strict as Tianjin and Guizhou. Heilongjiang did not suffer from the outbreak of SARS in 2003, and neither the government institutions nor residents have taken timely measures and control during the 2019 outbreak of the novel coronavirus. The mobility information of infected people did not expose in time. The public has not taken high regard for self-isolation. According to Sohu news, 94 percent of cases of infection are due to indoor congregation in Heilongjiang [11]. Furthermore, in accordance with Figure 9, Heilongjiang has 4 to 5 times of confirmed cases than Liaoning and

Jilin (Liaoning and Jilin have a similar geographical location as Heilongjiang, far from Hubei).