From: The UK Midwifery Study System (UKMidSS): a programme of work to establish a research infrastructure to carry out national studies of uncommon conditions and events in midwifery units
Exposure variable frequency in control group
Odds ratio detectable by the study
5 %
≥1.7
10 %
≥1.5
15 %
≥1.4
20 %
≥1.3
30 %
50 %
80 %