Table 1.
Quality evaluation of the included literature
| First author | Published year | Sample size | Study area | Research field type | quality sore |
|---|---|---|---|---|---|
| Yufang Bi | 2016 | 48 704 | all 31 provinces, autonomous regions, and municipalities in mainland China | nationwide | 7 |
| Ling Chen | 2015 | 302 | Bei Hai City, Guang Xi province | municipal | 7 |
| Zhenwang Fu | 2014 | 600 | Hai Nan province | provincial | 9 |
| Tianjing He | 2016 | 1724 | Hu Bei province | provincial | 5 |
| Kui Ji | 2015 | 2371 | Si Chuan province | provincial | 5 |
| Donghui Jin | 2015 | 2098 | Hu Nan province | provincial | 8 |
| Hua Li | 2015 | 2378 | He Bei province | provincial | 6 |
| Chunxia Liu | 2015 | 303 | Qin Huangdao city, He Bei province | municipal | 5 |
| Lixia Ma | 2014 | 610 | Ning Xia province | provincial | 5 |
| Xiuyun Sun | 2011 | 801 | Chongwen district, Beijing | district | 2 |
| Wenyun Wang | 2016 | 600 | Xiangshan city, Zhejiang province | municipal | 5 |
| Xiaofei wu | 2013 | 300 | Kashi city, Xingjiang province | municipal | 4 |
| Kaixu Xie | 2013 | 1800 | Tonxiang city, Zhejiang province | municipal | 6 |
| Wei Yan | 2015 | 1475 | Jiangxi province | provincial | 4 |
| Xin Yao | 2014 | 1500 | Inner Mongolia province | provincial | 5 |
| Chuanhua Yu | 2016 | 1800 | Hu Bei province | provincial | 5 |
| Yine Zhang | 2016 | 610 | Ning Xia province | provincial | 5 |
| Xiaohong Zhou | 2015 | 303 | Xia Chen district, Hangzhou city, Zhejiang province | district | 5 |
| Yingzhe Huang | 2013 | 306 | Binyang county, Guangxi province | district | 6 |
| Lei Qiao | 2010 | 880 | Beijing | municipal | 6 |
| Xin Meng | 2015 | 1493 | Ji Ling province | provincial | 9 |