In the estimation of domestic savings/ household savings in the state of Kerala and its availability for public investment for Indian states like Kerala, what sampling methodology and sampling sizes would be part?
Knowing nothing else about your goals, if you wish to sample all of the states you are interested in then use a stratified sample. If only some of them, use a cluster sample. See Schaeffer et al, Elementary Survey Sampling, Duxbury or Cochran, Sampling Techniques, Wiley, for details and how to calculate sample sizes. If you are only interested in Kerala, then use a simple random sample. Same references. Best wishes.