I have a population around 300,000 students who are in around 1000 schools. Out of these 1000 schools there are 50 "special schools". All schools fall into 70 districts (which are themselves in 14 zones). How should I think about sampling technique? [Multi-stage cluster or stratified etc.]
This is a case where I would like to take the students' opinion on a teaching tool and how they used it.
What should be the ideal sample size? In this regard I have a basic question: take Yamane's (1967) formula; what is exacty meant by confidence interval of 95%?