Table 1.

Sample selection, missing values and attrition

Criteria	Excluded	Total
Total subjects in NCDS Cohort at Age 16 years		16338
Private Schools	706	15632
Comprehensive school penetration rate > 80th percentile	2251	13381
Basic exclusions
Missing covariates, instrumental variable, outcomes at age 23	9933	3448
Further Exclusions
No overlap on predicted propensity score	20	3428