Table 2

Statistical power for various standardised effect sizes

iBV event rate	Sample size=150*		Rho	Statistical power
iBV event rate	With iBV	Normal microbiota	Rho	80%	85%	90%
10%	15	75	0.2	0.38	0.41	0.44
10%	15	75	0.3	0.45	0.48	0.52
10%	15	75	0.4	0.51	0.55	0.60
14%	21	69	0.2	0.33	0.36	0.39
14%	21	69	0.3	0.40	0.43	0.46
14%	21	69	0.4	0.45	0.49	0.52
18%	27	63	0.2	0.31		0.36
18%	27	63	0.3	0.37	0.39	0.43
18%	27	63	0.4	0.42	0.45	0.48

*We anticipate that the remaining participants will have an intermediate Nugent score of 4-6.
iBV, incident bacterial vaginosis.