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Table 1 Odds ratios detectable for given exposure variable frequencies1

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 % ≥1.3
50 % ≥1.3
80 % ≥1.4
  1. 1 80 % power at p < 0.05