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Table 1 Power calculation for policies assessment

From: The BLISS cluster randomised controlled trial of the effect of 'active dissemination of information' on standards of care for premature babies in England (BEADI) study protocol [ISRCTN89683698]

% with policy in control arm (p1)

% with policy in intervention arm (p2)

Size of effect (RR)

Total number of hospitals needed to detect with 80% power at 5% level of statistical significance (two-sided test)

60

82

1.4

126

55

78

1.4

124

50

74

1.5

121

45

69

1.5

126

40

64

1.6

128

35

59

1.6

128