Sample size update 2

Given the delays we are currently experiencing with initiating the impact evaluation study for 3ie, this document shows various operational scenarios and their implications on the study design so as to provide nuanced information to aid in planning and decision-making with regard to the study implementation. The scenarios we present here are based on an assumption that 3ie will be unwilling to move the end date of data collection. As it stands now, 3ie has stipulated that all data collection must end by October 2016. As per current design, this gives us a 10 month data collection period starting at

Sample size update 1

Stepped wedge study design We used the sample size calculations for a stepped wedge design proposed by Woertman et al1. Their calculations use the unadjusted sample size ($ n_{unadjusted} $) required for an individual randomised controlled trial for comparing two proportions and then adjusts this calculation based on the cluster design effect ($ DEFF $) to be expected in a stepped wedge design. Their equation for estimating the design effect of a stepped wedge study is as follows:   $$ DEFF_{\text {stepped wedge}} = \frac {1 + p(ktn + bn – 1)}{1 + p \left(\frac {1}{2}ktn + bn – 1

Sample size

Stepped wedge study design We used the sample size calculations for a stepped wedge design proposed by Woertman et al1. Their calculations use the unadjusted sample size ($ n_{unadjusted} $) required for an individual randomised controlled trial for comparing two proportions and then adjusts this calculation based on the cluster design effect ($ DEFF $) to be expected in a stepped wedge design. Their equation for estimating the design effect of a stepped wedge study is as follows:   $$ DEFF_{\text {stepped wedge}} = \frac {1 + p(ktn + bn – 1)}{1 + p \left(\frac {1}{2}ktn + bn – 1