Identify which of these types of sampling is used: random, systematic, convenience, stratified, or cluster. Upper A market researcher has partitioned all residents of a certain region into categories of young left parenthesis age 0 dash 30 right parenthesis comma middle aged left parenthesis age 31 dash 60 right parenthesis comma and senior left parenthesis over age 60 right parenthesis . She is surveying 46 people from each category.