Skip to main content

Table 5 Sample size required for various values of ICC and S

From: Clustering of continuous and binary outcomes at the general practice level in individually randomised studies in primary care - a review of 10 years of primary care trials

ICC = 0.01Balance of treatment arms within practicesS = 0
Perfectly balanced
S = 0.75
Slightly unbalanced
S = 2
Unbalanced
 Design effect0.990.99751.01
Trial size
150149150152
300297299303
500495499505
10009909981010
Design effect0.90.9751.1
Trial size
150135146165
300270293330
500450489550
10009009751100