Sampling Methods Summary

Sampling Techniques in Psychological Research

Key Definitions

  • Target Population: The entire group of individuals to whom the researchers want to generalize their findings.
  • Sample: A smaller group selected from the target population to participate in the research.
  • Sampling Bias: Occurs if the sample is not representative of the target population.

Sampling Techniques

Random Sampling

  • Description: Every member of the target population has an equal chance of being selected.
  • Strength: No researcher bias, more likely to produce a representative sample.
  • Weakness: Time-consuming, may still be unrepresentative if the sample size is small.

Opportunity Sampling

  • Description: Selecting participants who are available at the time of the study.
  • Strength: Quick and easy to do.
  • Weakness: Less likely to be representative, potential for researcher bias.

Volunteer Sampling

  • Description: Participants volunteer to be part of the study, often in response to an advert.
  • Strength: Quicker and easier to do, no researcher bias.
  • Weakness: Less likely to be representative, as only certain types of people volunteer.

Stratified Sampling

  • Description: Identifying subgroups (strata) within the target population and selecting participants in proportion to their representation in the population.
  • Strength: Most representative sampling method, no researcher bias.
  • Weakness: Time-consuming and difficult to carry out.

Evaluation of Sampling Methods (PBT Method)

The PBT method should be used to evaluate sampling methods:

  • Point: State the strength or weakness.
  • Explain: Elaborate on the point, use examples and evidence.
  • Because: Explain why the point is a strength or weakness and link it back to the question.

Applying Sampling Techniques

  • When applying stratified sampling, identify the strata, work out the proportions, and then use random selection within the strata.

Exam-Style Questions:

  • Difference between target population and sample.
  • Reasons why it might be difficult to generalize from a volunteer sample.