Table 1.

School level baseline characteristics by study group

		Control group (n=99)	Intervention group (n=102)
Strata
	Government-funded, ages 11–18 years, free school meals ≤17%	32 (32%)	34 (33%)
	Government-funded, ages 11–16 years, free school meals ≤17%	8 (8%)	8 (8%)
	Government-funded, ages 11–18 years, free school meals >17%	22 (22%)	24 (24%)
	Government-funded, ages 11–16 years, free school meals >17%	19 (19%)	18 (18%)
	Any residential school	5 (5%)	6 (6%)
	Special needs or alternate provision	5 (5%)	5 (5%)
	Further education college, ages ≥16 years	3 (3%)	2 (2%)
	Independent day school ≥500 pupils	3 (3%)	3 (3%)
	Independent day school <500 pupils	2 (2%)	2 (2%)
Students attending school		1014 (529–1376)	1025 (682–1359)
	Missing data	3 (3%)	1 (1%)
School staff		142 (91–189)	125 (91–173)
	Missing data	23 (23%)	17 (17%)

Data are n (%) or median (IQR). The number of students and staff at each school are based on participant lists provided as part of the study and for students from the UK Government Department for Education for schools not actively participating after random assignment. Four schools had missing student lists because schools stopped participating before these were provided and the school had not submitted student lists to the Department for Education previously. 40 schools had missing staff lists because schools stopped participating before these were provided and only student data were available from the Department for Education.