From: Vaginal progesterone to reduce preterm birth among HIV-infected pregnant women in Zambia: a feasibility study protocol
Observed proportion (adherence, retention)
0.5
0.6
0.7
0.8
0.9
0.95
Normal approximation of precision
±0.083
±0.081
±0.076
±0.066
±0.050
±0.036
Exact binomial 95% CI
0.41, 0.59
0.51, 0.68
0.62, 0.77
0.72, 0.86
0.84, 0.94
0.90, 0.98