Research question: Does a community-based dog rabies vaccination program increase the rabies vaccination coverage rate and reduce the incidence of human rabies?
Population of interest: Rural and urban counties of southern Kenya
Study design: This study would essentially incorporate a version of convenience sampling, since participating in the program would be voluntary. I propose using a stepped wedge design randomized cluster design, with the unit of randomization being village for rural counties and divisions for Mombasa. The intervention would entail offering free rabies vaccination clinics for domestic dogs at several time points during a calendar year, with villages or divisions randomized to the year the intervention took place. Vaccination coverage and rabies incidence would be compared for those in the intervention time period vs. control. Advantages of this plan are the relative ease and lower cost of simply offering a clinic rather than actively seeking out domestic dogs (e.g. going house-to-house) and enforcing vaccination. It is a more realistic intervention that has a better chance of being taken up by the ministry of health and continued as a regular government program.
Would this reduce bias in the estimation of univariate quatities? No, because this intervention will only be taken up by those who respond to the advertisement of the clinics. This is a population that is unlikely to be representative of the population of these villages or divisions as a whole, and different sub-populations are likely to have different prevalences of disease.
Would this reduce bias in the estimation of causal effects? Yes, because of the randomized stepped wedge design, we should be able to draw a causal inference on the effect of the intervention, assuming no other temporal trends are affecting the dog vaccination and rabies rates.