Children at a Kindergarten School Are Divided into Three Groups

Multiple Choice

Children at a Kindergarten school are divided into three groups: Those who are the oldest/first child (there are 200 of them, call this Group I) , those who are the second child (there are 150, call this Group II) , and those who are the third (or even fourth or fifth) child (there are 75, call this Group III) . The social worker at the school will take a sample to find out how many sleepovers they have had (without parents) at a friend's house. She suspects that first-borns do not get as many as later children, so she decides to take a simple random sample of 15 children from each of the three groups. What sampling technique will be used to obtain the sample of children?

A) stratified
B) cluster
C) simple random
D) multi-stage