Table 2.
Descriptive Statistics of Major Variables.
| Variable | Description | Mean | SD |
|---|---|---|---|
| IPD | Index of the prevalence of depression measured by search frequency of major depression-related words in Baidu using PCA method (log value) | 13.795 | 11.746 |
| PM2.5 | Weekly averaged PM2.5 100 mcg/m3 | 0.824 | 0.349 |
| Internet | Internet usage measured by the frequency of surfing 11 major websites | 0.018 | 1.009 |
| Daylen | Weekly averaged day length multiplied by the weekly ratio of sunny day | 3.298 | 3.038 |
| Tem | Weekly averaged day mean temperature | 16.113 | 10.509 |
| Rain | Weekly ratio of rainy days | 0.267 | 0.242 |
| Wind | Weekly averaged wind speed | 13.795 | 11.746 |