Definitions and scores
Previous studies have demonstrated that the SCL-90-R tests have good
internal consistency, reliability, and validity (Li et al., 2015).
Overall mental health status was evaluated via 3 global scales: 1. The
Global Severity Index (GSI), indicating a global scale; 2. Positive
Symptom Total (PST), expressing all items more than 1 point to display
number of items did the subjects presenting symptoms; and 3. Positive
Symptom Distress Index (PSDI), meaning the sum of values of none-zero
items by PST, reflecting the extent of severity of items that subjects
feel bad about themselves. Higher score indicated more seriously mental
health status.