Table 3 Summary of the factorial design of the simulation study for the secondary objective

Number of clusters in each treatment arm (K)

9

Number of observations per cluster (M)

300

Intra-cluster correlation (ρ)

0.05

Standardised treatment effect (θ)

0 or 0.5

Number of covariates in the data generation model (L)

4, 8, 12

Magnitude of prognostic effect of covariates

0.25, 0.5, 1.0

Number of covariates balanced in the randomisation (C)

1, 2, 3, 4

Candidate set

100% (simple randomisation)

Number of covariates adjusted in the analysis (A)

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12