I work in epidemiology on a sample which is stratified, and 2 – level cluster (801 individuals). I use the "survey" package on R for data analysis.
In the sample, the sum of weights is the size of estimated population.
When I calculate prevalence in sample 1 with weights or normalised weights, the results were the same, but I thought the confidence interval could be impacted and the variance too. Why it is not the case?
Thanks you in advance,