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 4

Association between multilevel analysis and study characteristics and power analysis: median (Q1, Q3), N (%).

Study characteristics	Multilevel analysis		value
	Yes ()	No ()
Number of schools	16 (8, 32)	10 (6, 18)	0.030
Analytic sample size	816 (432, 1323)	472 (181, 869)	0.002
Follow-up length in months	12 (6, 24)	7 (4, 18)	0.014
Number of measurements	2 (2, 3)	2 (2, 3)	0.558
Randomization at a cluster level	82 (98.8%)	26 (68.4%)	<0.001
Follow-up ≥1 year	52 (62.7%)	16 (42.1%)	0.048
Two measurements including baseline	47 (56.6%)	23 (60.5%)	0.843
Trials conducted outside the US	47 (56.6%)	22 (57.9%)	1.000
Power analysis and ICC
Power analysis conducted and reported	39 (47.0%)	13 (34.2%)	0.236
ICC taken into account for power analysis	23 (27.7%)	3 (7.9%)	0.016
ICC estimated from the analysis reported	10 (12.1%)	0 (0.0%)	0.030

is missing.