Results
All participants were asked to complete a questionnaire that included gender, age, grade, height, weight, whether they were an only child, whether their home address was town or village, monthly household income, GPA for the previous school year, and disposable income. Specific issues and analysis results are shown in Table 1 . As shown in Table 1 , there are significant differences in the mean of AA scores across grade levels and BMI index (F = 3.402 P = 0.009; F = 5.752 P = 0.003). IS scores varied significantly by grade levels, home address, and ranking of results (F = 2.738, P = 0.028; F = 2.113 P = 0.035; F = –2.426 P = 0.016). The average scores of SS varied significantly across gender, grade, BMI, only a child, home address, monthly income, ranking of results, single and discretionary income (F = 2.228 P = 0.026; F = 2.682 P = 0.031; F = 3.367 P = 0.001; F = −3.004 P = 0.003; F = −5.289 P < 0.000; F = 2.801 P = 0.005; F = 1.985 P = 0.048; F = −3.584 P < 0.000). The mean of Depression scores varied with grade levels and ranking of results (F = 2.679 P = 0.031; F = −2.885 P = 0.004).

The correlation matrix of key study variables is presented in Table 2 . IS and AA were positively correlated (r = 0.568, P < 0.01); AA and IS were negatively correlated with SS (AA: r = −0.323, P < 0.01; IS: r = −0.319, P < 0.01); AA and IS were positively correlated with depression (AA: r = 0.438, P < 0.01; IS: r = 0.534, P < 0.01), and SS was negatively correlated with depression (r = −0.344, P < 0.01).

Note:

A multiple mediation analysis was conducted to explore the mediation effects of IS and SS in a college student population. Control variables included gender, age, BMI, GPA, being an only child or not, and home address. AA and depression were entered as independent and dependent variables respectively. The proposed mediators were IS and SS. Results of the analysis ( Table 3 ) showed that AA was positively correlated with depression (Index = 0.168, P < 0.001). Secondly, AA was positively correlated with IS (Index = 0.575, P < 0.001) and negatively correlated with SS (Index = −0.234, P < 0.001). IS was negatively correlated with SS (Index = −0.179, P < 0.001). In addition, IS was positively correlated with depression (Index = 0.384, P < 0.001) and SS and depression were negatively correlated (Index = −0.161, P < 0.001).

Notes:

β is the normalization factor.

The mediation path model is presented in Figure 1 . To test the significance of the mediating effect of IS and SS, a bootstrap estimation procedure with 5,000 bootstrap samples is performed. The total effect, direct effect, and indirect effect are presented in Table 4 . The path coefficients for the 95% CI of the paths do not include 0 which means that the path coefficient of this path is significantly true at the level of 0.05. As is shown in Table 4 , the significance of the direct effect of AA on depression (Effect = 0.081, 95% CI [0.045–0.117]) remained when the mediators (IS and SS) were included in the model. AA was found to indirectly affect depression psychological stress through three significant mediation pathways: (1) IS (B = 0.106, 95% CI [0.082–0.132]), which accounted for 49.77% of the total effect, (2) SS (B = 0.018, 95% CI [0.008–0.031]), which accounted for 8.45% of the total effect, and (3) IS and SS (B = 0.008, 95% CI [0.003–0.014]), which accounted for 3.76% of the total effect. The total mediating effect was 61.97%.