AL: Sample Selection and Sampling Methods/Techniques

Psychology is about creating general laws or principles, which allow us to predict how people might behave in specific situation. When we conduct psychological studies we cannot test everyone, so we work with a small number of people known as participants who collectively are known as the sample.

If the sample are considered to be representative of the target population, or the group of people whose behaviour we wish to predict, then we can say that our findings are generalisable. To be representative our sample must comprise a group of people who share similar characteristics to those in the target population.

There are various different ways of obtaining a sample and they differ with regards to how representative the sample is likely to be, therefore the choice of sampling technique will directly affect the generalisability of the study.

You need to know about 4 sampling methods:

  • Random
  • Volunteer
  • Opportunity/Convenience
  • Stratified

The resources here will help you to learn more about sampling.





sampling-sheet This link will take you to my sampling progress check quiz.

Revision: sampling revision IB

Practice Questions:

  1. Beryl has conducted a study for a local health authority looking at the development of play in infants aged one to two years old. As the local population includes many different ethnic groups, Beryl has made sure that she has included the same percentage of each ethnic group in her sample as there is in the target population. Beryl’s sampling method is

A volunteer

B opportunity

C stratified

D random

2. Megan is ding an experiment involving children at a local primary school. She is only going into the school on one day to carry out her experiment so she has to use the children who are in the school on that day. Megan’s sampling method is

A random

B volunteer

C opportunity

D stratified

3. Explain one weakness of Megan’s experiment (2)