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]

Table 2 Power calculation for changes in practice for various assumptions of % with practice pre-intervention – p₁(20–60%), p₂ (30–90%), assuming 80% power at 5% level of statistical significance (2-sided test), for sizes of effect ≤ 2 and assuming no clustering (ie ICC = 0.00)

Total number of babies needed
p ₁	P ₂
	30	35	40	45	50	55	60	65	70	75	80	85	90
60									712	304	162	98	62
55								752	324	176	108	70	48
50							774	338	186	116	76	54	38
45						782	346	192	120	82	58	42	32
40					774	346	194	122	84	60	44
35				752	388	192	122	84	62
30			712	324	186	120	84
25		656	304	176	116
20	546	276	162