Lecture Notes: Sampling in Research Methods

Introduction

• Target Population: Every individual that forms part of the group being studied.
  • Typically a very large number.
  • Purpose: To generalize findings from the sample to the target population.
• Generalization: Applying sample results back to the target population.
• Representativeness: Ideally, samples should represent the larger population.

Sampling Techniques

1. Random Sampling

• Definition: Every individual has an equal chance of being selected.
• Process: Requires a complete list of the population and random selection (e.g., drawing names from a hat or using a random number generator).
• Strengths:
  • Avoids researcher bias.
• Weaknesses:
  • May still result in an unrepresentative sample.
  • Time-consuming for large populations.

2. Systematic Sampling

• Definition: Selection of every Nth individual from a list.
• Process: Uses an ordered list (e.g., a register).
• Strengths:
  • Reduces researcher bias.
  • Efficient with small, already listed populations.
• Weaknesses:
  • Possibility of unrepresentative samples.
  • Challenging with large populations without a full list.

3. Opportunity Sampling

• Definition: Use of readily available individuals.
• Process: Participants included by researcher’s accessibility.
• Strengths:
  • Quick and cost-effective.
• Weaknesses:
  • High potential for researcher bias.
  • Usually non-representative (e.g., only certain demographics like university students).

4. Volunteer Sampling

• Also Known As: Self-selecting sample.
• Definition: Participants volunteer themselves, usually through advertisements.
• Strengths:
  • Broad reach through ads.
  • Easy collection process.
• Weaknesses:
  • Volunteer bias (attracts specific types of individuals, e.g., those with free time).

5. Stratified Sampling

• Definition: Creates a sample that mirrors the population's subgroups.
• Process: Identifies important subgroups and randomly selects participants from each.
• Strengths:
  • Highly representative of the larger population.
  • Minimizes researcher bias.
• Weaknesses:
  • Potential bias in subgroup selection.
  • Time-consuming and complex.

Additional Considerations

WEIRD Participants

• Criticism: Many psychology studies disproportionately involve western, educated, industrial, rich, and democratic individuals.
• Implications: Lack of global generalization; possible gender bias in historical studies.

Conclusion

• Emphasis on understanding sampling methods to ensure valid generalizations in research.
• Acknowledgement of supporter contributions on Patreon allowing for ongoing educational resource development.