Statistical analysis
Descriptive analyses were performed for all variables. The Shapiro–Wilk test was used to test the normal distribution of continuous variables. We revised the analytical plan after the registration because of differences in age and sex between the cohorts (see Table 1). A stepwise regression controlling for these differences and involving a dummy code to compare the behavior before and during quarantine (0 =before quarantine, 1 = after quarantine) was conducted. To determine the differences between the two groups (before and after quarantine) and cohorts (data obtained from the first and second questionnaires), we used the t-test, chi-square test, and Fisher’s exact test when appropriate. Univariate and multivariate correlations were also determined. We followed up with multiple regressions predicting variables of interest and potential moderators (main effect and interaction with COVID-19 stress) associated with COVID- 19 stress. Categorical moderators were dummy-coded (i.e., sex: 0 = men, 1 = women).
Statistical Package for the Social Sciences (SPSS v25) was used for statistical analysis, and a two-tailed p-value < 0.05 was considered significant. Missing values were excluded from the analysis.