A Researcher Invokes a Pilot Sample and Finds That Respondents

Essay

A researcher invokes a pilot sample and finds that respondents from households
with less than $50,000 annual income respond very differently than respondents from households with greater than $50,000 annual income,with regard to the key survey questions.In addition,the researcher's preliminary results show greater variance among respondents in the over $50,000 households.Given the preceding,which probability sampling method should the researcher invoke and why?