Table 1.

Precision estimates for effect sizes given varied assumptions about control-arm prevalence and between-community variation

Outcome	Estimated final sample size per site (with 4 intervention and 4 control sites in total)	Estimated prevalence of outcome measure		Effect estimate	Estimate of precision of percentage risk difference (95% CI)*
		Control arm (%)	Intervention arm (%)	Risk difference (%)	k = 0.1	k = 0.2	k = 0.3	k = 0.4
Past year experience of physical IPV (women partnered in past year)	75 (based on 100 respondents per site, 80% having partner in past year and 5% non-response to violence questions)	30.0	22.5	7.5	−2.4, 17.4a	−5.2, 20.2 a	−8.8, 23.8 a	−12.9, 27.9 a
		30.0	15.0	15.0	5.8, 24.2	3.4, 26.6	0.2, 29.8	−3.4, 33.4 a
		20.0	15.0	5.0	−3.2, 13.2 a	−4.7, 14.7 a	−6.9, 16. 9 a	−9.4, 19.4 a
		20.0	10.0	10.0	2.4, 17.6	1.1, 18.9	−0.8, 20.8 a	−3.0, 23.0 a
Past year experience of sexual IPV (women partnered in past year)	75 (based on 100 respondents per site, 80% having partner in past year and 5% non-response to violence questions)	15.0	11.0	4.0	−3.1, 11.1 a	−4.1, 12.1 a	−5.6, 13.6 a	−7.3, 15.3 a
		15.0	7.5	7.5	0.9, 14.1	0.0, 15.0	−1.3, 16.3 a	−2.8, 17.8 a
		10.0	7.5	2.5	−3.4, 8.4 a	−3.9, 8.9 a	−4.8, 9.8 a	−5.8, 10.8 a
		10.0	5.0	5.0	−0.4, 10.4 a	−0.9, 10.9 a	−1.7, 11.7 a	−2.6, 12.6 a
Concurrent sexual partners (among non-polygamous men partnered in the past year)	75 (based on 100 respondents per site, 80% having partner in past year and 5% non-response to sexual behaviour questions)	50.0	37.5	12.5	0.0, 25.0	−5.7, 30.7 a	−12.5, 37.5 a	−19.7, 44.7 a
		50.0	25.0	25.0	13.4, 36.6	8.4, 41.6	2.4, 47.6	−3.9, 53.9 a
		40.0	30.0	10.0	−1.3, 21.3 a	−5.5, 25.5 a	−10.7, 30.7 a	−16.3, 36.3 a
		40.0	20.0	20.0	9.5, 30.5	5.9, 34.1	1.3, 38.7	−3.7, 43.7 a

*Based on calculations provided by Hayes and Bennet (1999) [58].

^aNo statistically significant difference between intervention and control groups.

IPV, intimate partner violence.