Table 1.
Components in intervention and control groups
| Group | Site | Number of Subjects | Location |
|---|---|---|---|
| Intervention | Kindergarten affiliated to the organ of 4th engineering bureau of the Railway Ministry | 266 | West urban Hefei district |
| Kindergarten affiliated to telegraphic bureau of Hefei | 180 | West urban Hefei district | |
| Kindergarten affiliated to Anhui Medical University | 106 | West urban Hefei district | |
| Suzhou road kindergarten | 430 | Center urban Hefei district | |
| The 1st kindergarten affiliated to Hefei Steel company | 270 | East urban Hefei district | |
| Subtotal | 1252 | ||
| Control | Kindergarten affiliated to Hefei Technical University | 280 | West urban Hefei district |
| Kindergarten affiliated to the organ of the Hefei city Government | 390 | Center urban Hefei district | |
| The 2nd kindergarten affiliated to Hefei Steel Company | 180 | East urban Hefei district | |
| Subtotal | 850 | ||
| Total | 2102 |