Trial Characteristics and Appropriateness of Statistical Methods Applied for Design and Analysis of Randomized School-Based Studies Addressing Weight-Related Issues: A Literature Review

Table 2

Study characteristics by study years: median (Q1, Q3), N (%).

Study characteristics	All years ()	1995–2012 ()	2013–2017 ()	value
Number of schools	13 (7, 28)	14 (8, 31)	12 (6, 20)	0.434
Analytic sample size	620 (340, 1182)	670 (407, 1295)	610 (310, 1083)	0.269
Follow-up length in months	12 (6, 24)	12 (6, 24)	12 (5, 20)	0.078
Number of repeated measurements	2 (2, 3)	2 (2, 3)	2 (2, 3)	0.098
Randomization at a cluster level	108 (89.3%)	57 (90.5%)	51 (87.9%)	0.772
Follow-up ≥1 year	68 (56.2%)	38 (60.3%)	30 (51.7%)	0.365
Two measurements including baseline	70 (57.9%)	32 (50.8%)	38 (65.5%)	0.140
Trials conducted outside the US	69 (57.0%)	32 (50.8%)	37 (63.8%)	0.198
School type				0.038
Preschool	11 (9.1%)	3 (4.8%)	8 (13.8%)
Primary/elementary school	83 (68.6%)	50 (79.4%)	33 (56.9%)
Middle school	20 (16.5%)	7 (11.1%)	13 (22.4%)
High school	5 (4.1%)	3 (4.8%)	2 (3.5%)
College	2 (1.7%)	0 (0.0%)	2 (3.5%)

is missing.