2.1. Sampling Method
Firstly. the sample size needed for the study was calculated using the G*Power 3.19 program. When calculated based on parameters of the two-sided test, χ2 test, a residual variance of 0.83, α probability = 0.05, and power = 0.95 for F tests and linear multiple regression analysis, the minimum total sample size was estimated to be 356 overall.
Secondly, 461 respondents were finally collected in this study from 23 March to 12 April 2020[1] via Snowball Sampling method (recruit respondents from among acquaintances). Respondents were 180 Chinese in South Korea collected during March 23-April 8, 2020, and 281 Chinese in mainland China during April 2-12, 2020. In line with the research aim, which was to survey college students, the respondents of those who stated “Employed”, “Unemployed” and “Others” in the occupation question were removed, leaving a total of 420 students (171 Chinese in South Korea, named as “International Group”, and 249 Chinese in mainland China, named as “Mainland Group”). All respondents expressed a willingness to participate and understand the background and purpose of the study.
2.2. Data Collection
The online questionnaire surveys were distributed using the Naver Online Survey (Tool) for International Group and Surveystar Online Survey (Tool) for Mainland Group respectively. The questionnaires for the two groups were at the same design and written in Simplified Chinese Characters. Before conducting the survey, we did the revision and verification of the contents of the questionnaire through the online pilot survey and to make sure that the statements are appropriate and understandable. During the initial screening of the online questionnaire, the purpose of the research, and the confidentiality and privacy of individuals was ensured in written format on the first page of the survey questionnaire. Only after reading and clicking “AGREE” to make the consent, the filling of the questionnaire could begin. In addition, we stipulated that the main questions in the survey were mandatory questions, which means the participants have to complete all answers before they submitted the online questionnaire. All the measures above made the response rate of our study was 100%.
2.3. Research Tools
This study was combined with 1) YGHC COVID-19 Online Survey Tool and 2) Patient Health Questionnaire-9. YGHC COVID-19 Online Survey Tool was designed and updated by Yonsei Global Health Center (YGHC), aiming to evaluate the target respondents’ basic demographics characteristics, knowledge about COVID-19, preventive practices against COVID-19, depressive symptoms. Questions in the YGHC COVID-19 Online Survey Tool were found to own a reasonable validity and reliability in Wang’s research on the Chinese general population [15]. YGHC made changes on Part E (Precaution measures) and Part F (Additional information) according to the specific situation in the two countries. The Patient Health Questionnaire-9 (PHQ-9) was added to the study to provide a baseline for the incidence of depression.
2.4. Variables Description
2.4.1. General Demographics Data
In this study, to reflect the demographic characteristics of the respondents, the basic survey asked questions related to: “sex”, “age”, “education level”, “marital status”, “family size”, “whether you had medical insurance”, “whether you had chronic diseases”, “whether you had traveled abroad in the past 14 days”, and “whether you had experienced quarantine”. The educational level was divided into “Undergraduate” and “Graduate”, and the marriage status comprised of “Single” and “Married”. Family size includes “1-person family”, “2-person family”, “3~5 persons family” and “more than 6-member family”. The questions about having “Medical insurance”, “Chronic illness”, “Travelled abroad”, and “Self-quarantined” had two possible answers: “no” and “yes”. The question about the “Self-assessed physical condition” was also included: “above good” and “below fair”.
2.4.2. Knowledge and perception about COVID-19
Understanding and perception of COVID-19 and other topics were assigned in a self-enumeration questionnaire, including knowledge on transmission pathway, information satisfaction, sources of related information, confidence about diagnose, degree of concern about this disease, perceived probability, and concern about family members.
2.4.3. Preventive practices of COVID-19
Nine basic preventive practices were incorporated into the questionnaire. We gave the score corresponding to the degree to which a measure was practiced on a daily basis (1 = “Never do this” and 5 = “Do this every day”) and added total points to all the questions to calculate the total preventive practices. Cronbach's Alpha coefficient of preventive practices of the COVID-19 scale was 0.78.
2.4.4. Patient Health Questionnaire-9
Depressive symptoms could be diagnosed based on the 9 criteria for depression in the Diagnostic and Statistical Manual of Mental Disorders published by the American Psychiatric Association [40]. To understand the response to these question, each question was divided into 4 categories:“not at all” (0 points), “several days” (1 point), “more than half the days” (2 points), and “almost every day” (3 points) [41]. According to the scoring criteria, the score on PHQ-9 was divided into five groups: 0–4, 5–9, 10–14, 15–19, 20–27, which corresponded to “minimal or none”, “mild”, “moderate”, “moderately severe”, and “severe” depression, respectively [42]. The higher the score, the more intense the level of depression.
The symptoms of depression were able to be assessed based on the 10 scores in PHQ-9. With a sensitivity of 88% and a specificity of 88% for detecting major depressive disorders, a score of 10 has been recommended as the cut-off score for diagnosing depression [43]. Thus, in this study, 10 and more points were classified as “moderate-to-severe”, and less than 10 points were classified as “minimal-to-mild”. Cronbach's Alpha coefficient of the scale in this study was 0.89.
2.5. Statistical Analysis Approach
In this study, STATA 15·0 and SPSS 24·0 were used to conduct statistical analysis. The specific analytical methods are as follows:
- Firstly, descriptive statistics, t-test, and Chi-squared tests were performed in each variable between “International Group” and “Mainland Group”.
(2) Secondly, to explore the determinants of the different depression levels, hierarchical regression was performed.
[1] From WHO, date as of 31 March 2020: China: Total confirmed cases 82,545, total deaths 3314; Korea: Total confirmed cases 9,786, total death 162