Table 5.

Powers and average sample sizes for the GEE method with and without sample size re-estimation.

ICC of standard CPR group	ICC of high performance CPR group	n1	nmax	Power without SSR, %	Power with SSR, %	Favorable, %	Promising, %	Unfavorable, %	Average of final sample size after SSR
0.003	0.003	1800	3500	80	79	58	16	27	3066
0.032	0.032	1800	3500	73	72	51	16	33	3066
0.032	0.003	1800	3500	72	72	51	15	33	3065
0.032	0.032	1800	4000	80	80	58	15	27	3101
0.032	0.003	1800	4000	73	73	50	17	33	3111
0.003	0.003	2400	3500	72	73	51	16	33	3108
0.032	0.003	2400	3500	80	79	64	11	25	3042
0.003	0.003	2400	4000	73	72	56	12	31	3047
0.032	0.032	2400	4000	72	72	56	12	31	3048
0.032	0.003	2400	4000	80	80	65	11	24	3068

GEE: generalized estimating equation, ICC: intra-cluster correlation coefficient, CPR: cardiopulmonary resuscitation, n₁: sample size at interim analysis, n_max: permitted maximum sample size, SSR: sample size re-estimation.