Table 5.

Methods of analysis and reporting of correlation coefficients (N=62)

Characteristic	Frequency (%)
Did primary analysis of primary outcome account for clustering?
Cluster randomized trials (N=38)
Yes: Analysis was at individual-level accounting for clustering	20 (52.6%)
Yes: Analysis was at cluster-level	3 (7.9%)
Yes: Othera	2 (5.3%)
No: Analysis was at individual-level not accounting for clustering	11 (28.9%)
No: Clustering effect was small; proceeded without accounting for clustering	1 (2.6%)
Unclear whether accounted for clustering	1 (2.6%)
Individually randomized group treatment trial (N=9)
Yes: Analysis was at individual-level accounting for clustering	1 (11.1%)
No: Analysis was at individual-level not accounting for clustering	7 (77.8%)
No: Clustering effect was small; proceeded without accounting for clustering	1 (11.1%)
Were repeated measures utilized in primary analysis of the primary outcome? (N=54)
Yes	35 (64.8%)
No	19 (35.2%)
Was correlation in dyadic or multivariate outcome accounted for in analysis? (N=17)
Yes	1 (5.9%)
No	16 (94.1%)
Reported any correlation coefficients?
Trials with potential intracluster correlation (N=47)	17 (36.2%)
Trials with potential correlation over time (N=54)	0
Trials with potential correlation between multivariate outcomes (N=17)	0
Methods of analysis
Simple method (e.g., t-test, chi-squared test)	9 (14.5%)
Generalized Estimating Equations (GEE)	11 (17.7%)
Mixed-effects regression	22 (35.5%)
Fixed-effects regression	16 (25.8%)
Other (e.g., structural equation modeling, MANCOVA, two-stage method)	4 (6.5%)

^aOne trial conducted analyses at both individual-level accounting for clustering and cluster-level; one trial used a two-stage method: in stage one ANCOVA was used within each cluster-pair; in stage two random effects meta-analysis was used