Abstract: In the field of psychology, traditional meta-analysis methods have mainly been used to quantitatively examine the typical effect size of homogenous studies about the same issues. However, there is a great variance in effect sizes in studies across different publication years, which has been regarded as random errors and consequently neglected in general. In the present study, we introduced a new approach known as cross-temporal meta-analysis (Twenge, 2000, 2001, 2002, 2007, etc.). This method was applied to examine the changes of Chinese middle school students’ mental health from 1992 to 2005 in this study. We also investigated correlations between 10 social indices, which have been categorized into three aspects (social connectedness, educational conditions and economic states), and SCL–90 scores.
Using cross-temporal meta-analysis, the present study examined changes over time of Chinese middle school students’ scores on the Symptom Checklist 90 (SCL–90) in the past 14 years. One hundred and seven previous studies published or unpublished of mental health of middle school students (N = 111925) were included in the data.
The results showed that: (1) Moderate correlations were found between seven of nine SCL–90 dimensions and year of data collection (0.22~0.35), suggesting that the mental health of Chinese middle school students has been slowly decreasing over time. (2) Correlations between the standard deviation of SCL–90 scores and year of data collection were positive (0.19~0.38), suggesting that Chinese middle school students’ mental health level was more diverse than before. (3) Correlations between ten social indices and SCL–90 scores were positive, suggesting that changes on the three kinds of social factors may be responsible for the decrease in middle school students’ mental health.
This may be the first study using cross-temporal meta-analysis to highlight whether Chinese middle school students’ mental health decrease in the context of rapid social change in contemporary China. Because of the decrease of Chinese middle school students’ mental health, more attention should be paid on them

Key words: middle school students, mental health, SCL–90, cross-temporal meta-analysis, meta-analysis