Table 3. Sampling strategy for coordinated TAS and STH surveys.
| LF (TAS) | STH survey | |||||
| Country | Evaluation unit | Survey design | Target sample size | Number of ecological zones in EU | Target number of schools surveyed1 | Target sample size |
| Benin | Tchaourou (district) | Cluster survey of 30 schools | 1,552 (1st–2nd grade) | 1 | 5 | 250 (1st–2nd grade) 250 (3rd grade) |
| Tonga | Tongatapu, Vava'u, Ha'apai (island groups) | Census of 127 schools | 3,293 (1st grade) | 2 | 10 | 500 (3rd grade) |
1
5 schools per ecological zone; all schools randomly selected from TAS sample except two schools in Tonga that were included in 2001–2002 STH survey.