Table 7.

Coverage of the 95% interval estimate of the treatment effect and statistical power of Models A - E in scenarios 4 to 6

	ICC = 0.01		ICC = 0.05		ICC = 0.20
Model	Cover. of CI	Power	Cover. of CI	Power	Cover. of CI	Power
Scenario 4 - chance imbalance, 45 centres each with 4 subjects
A	0.954	0.910	0.949	0.918	0.942	0.845
B	0.966	0.846	0.946	0.822	0.931	0.810
C	0.954	0.912	0.945	0.917	0.934	0.870
D	0.948	0.924	0.934	0.926	0.934	0.878
E-1	0.411	0.782	0.417	0.793	0.424	0.745
E-2	0.897	0.468	0.900	0.501	0.887	0.468
Scenario 5 - chance imbalance, 18 centres each with 10 subjects
A	0.954	0.898	0.949	0.900	0.942	0.843
B	0.946	0.874	0.959	0.891	0.937	0.891
C	0.952	0.898	0.951	0.904	0.939	0.895
D	0.922	0.916	0.932	0.911	0.910	0.900
E-1	0.776	0.868	0.794	0.890	0.791	0.895
E-2	0.905	0.810	0.918	0.834	0.918	0.839
Scenario 6 - chance imbalance, 6 centres each with 30 subjects
A	0.950	0.897	0.953	0.905	0.961	0.860
B	0.949	0.892	0.954	0.907	0.961	0.916
C	0.950	0.897	0.952	0.905	0.959	0.910
D	0.856	0.911	0.879	0.918	0.874	0.908
E-1	0.922	0.904	0.931	0.921	0.931	0.913
E-2	0.944	0.831	0.951	0.867	0.955	0.857

Cover. of CI: coverage proportion of 95% confidence interval; ICC: intraclass (intracentre) correlation