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Table 4 Power for comparison of HIV incidence between Arms A and B, with 7 communities per arm and Population Cohort of 2,500 adults per community (assuming that on average 2,125 (85%) will be HIV-uninfected at baseline and that loss to follow-up will be 20% after 2 years and 25% after 3 years)

From: HPTN 071 (PopART): Rationale and design of a cluster-randomised trial of the population impact of an HIV combination prevention intervention including universal testing and treatment – a study protocol for a cluster randomised trial

HIV incidence rate/100 py (control arm) Between-cluster coefficient of variation (k) Effectiveness (%) Arm A Effectiveness (%) Arm B Power (%)
1.0 0.15 50% 20% 89%
1.0 0.15 50% 25% 78%
1.0 0.15 55% 25% 92%
1.0 0.15 55% 30% 82%
1.0 0.15 60% 25% 98%
1.0 0.15 60% 30% 94%
1.0 0.15 65% 25% 99%
1.0 0.15 65% 30% 99%
1.0 0.20 50% 20% 78%
1.0 0.20 50% 25% 65%
1.0 0.20 55% 25% 83%
1.0 0.20 55% 30% 71%
1.0 0.20 60% 25% 93%
1.0 0.20 60% 30% 87%
1.0 0.20 65% 25% 98%
1.0 0.20 65% 30% 96%
1.5 0.15 50% 20% 94%
1.5 0.15 50% 25% 86%
1.5 0.15 55% 25% 96%
1.5 0.15 55% 30% 90%
1.5 0.15 60% 25% 99%
1.5 0.15 60% 30% 98%
1.0 0.20 65% 25% 99%
1.0 0.20 65% 30% 99%
1.5 0.20 50% 20% 84%
1.5 0.20 50% 25% 72%
1.5 0.20 55% 25% 88%
1.5 0.20 55% 30% 78%
1.5 0.20 60% 25% 96%
1.5 0.20 60% 30% 92%
1.0 0.20 65% 25% 99%
1.0 0.20 65% 30% 98%