I want to conduct a research to assess the success, challenges, and outcomes of the OPV vaccination program over the last 15-20 years. I need a model which can be applied to this research.
I think you may use a mixed method evaluation approach.You may use quant methods to assess success in terms service uptake and outcomes. If you have baseline data, you may compare your variables before and after using unpaired t tests analysis to see if there are any changes in the outcomes. You may use qualitative approach to interview service users and beneficiaries for benefits, challenges and areas for improvement
For a Health programme assessment Study which model to use. I would like to add to what my colleagues here have said and this is not a WHO position but my mere ideas from my own experience since I was involved in Health programmes and projects assessment. You need to be specific on which programme you want to assess; programme about what ? For just an example: Heart Diseases prevention programme assessment: Questions to be asked first of all: What are the vision , the mission, the Terms of Reference including the objectives and its Plan Of Action of that programme. From there you have to check adequacy between the ToR etc using the following criteria: Relevance, sustainability, impact, effectiveness, efficiency, efficacy, cost of that programme. You need to use a checklist where you pick from the field where the programme is being implemented the following questions and topics: Vision, mission, inputs, process, outputs and outcome and use the related health indicators plus coverage ...Use also quantitative and qualitative approaches in Operational Research and Action Research etc. I hope it can help.