Improving Lifejacket Wear Among Boaters on Lake Albert, Uganda. A Cluster-randomized Trial

Given that the intervention will be at the community level, a cluster randomized controlled trial is considered most appropriate for testing the hypothesis of this study. The intact groups/clusters of individuals (boaters) rather than individuals themselves, will be randomized to either intervention or control arm. The landing sites herein referred to as clusters, will be the randomization unit. This is because it is difficult to randomize individuals to behavioral intervention since they mix within the cluster. This study will be conducted using an etic epistemological approach guided by a realist ontology in order to objectively measure the effect of the intervention without the influence of the researchers.

To reduce covariate imbalance and increase comparability at baseline, clusters will be randomized to either intervention or control arm using stratified permuted block randomization, with landing sites (clusters) as the randomization unit. The clusters will be stratified by estimated population size and baseline prevalence of lifejacket use as compared with the overall average prevalence. All individuals in the intervention cluster will receive the intervention. The main aim of the stratified randomization is to ensure that the clusters are as comparable as possible at baseline. The other factors that might be considered for stratification will be identified at baseline and, in the opinion of the investigator, might interfere with the objectives of the study. Because there are few clusters per arm (7), two strata will be formed. The stratification variable will be the baseline prevalence of lifejacket wear in the landing sites.

The risk of contamination (one of the major threats to this study) will be reduced by ensuring that at least one cluster which is not part of the study acts as a buffer. From each stratum, one cluster will be randomly allocated to the intervention arm and the other to the control arm using stratified permuted block randomization with a 1:1 allocation ratio. The allocation will be generated using the 'sealed envelope TM' web-based application by an independent statistician who has no interest in the study. The block sizes will be masked/blinded to increase the randomness.