Question

Question 2. Which of the following describes stratified random sampling? Explain why it is correct and why it is incorrect

1. The first 95% of the people who respond to a mailed survey make up the sample, while the remaining 5% are not included because they constitute the 5% late-error-rate.

2. The first half of a volunteer sample that shows up is put in a group together-and the second half is grouped together. Thus, we are left with a sample with two sub groups (subgroups A and B).

3. Proportions of subgroups are chosen based on the fact that 60% of the population is right -handed and 40% is left handed. So 60% of the participants chosen are also left-handed and 40% of those chosen are right handed.

4. For a study on charter schools in Manhattan, a list of the Charter schools in the area is generated and participants are then randomly selected from each school (sub-group).

Answer 1

Stratified sampling scheme is a sampling plan where in the population is sub divided into homogenous groups which are heterogeneous within themselves and then individuals are selected randomly from each group which constitutes our sample.

From the following described schemes, the case of study of charter schools in Manhattan is stratified random sampling because groups of charter schools in areas are formed and then sampling units are selected in a random manner from each group.

Whereas the remaining are not stratified random sampling as the stratification has not been done on the basis of similarities of units. Some different criteria has been followed to form the sub groups.