Sampling Opportunities
What Is Opportunity Sampling?
Opportunity sampling (also called convenience sampling) is a non-probability sampling method where participants are selected based on their availability and willingness to take part in a study. It is widely used in psychological research due to its ease and efficiency.
For example, a psychologist conducting an experiment in a school may recruit students available in a classroom rather than selecting participants randomly from the entire student population.
Key Features of Opportunity Sampling:
✅ Quick and easy to conduct – Participants are selected based on convenience, making it a fast method.
✅ Common in psychological research – Frequently used in field studies and classroom-based experiments.
✅ May lack representativeness – Since participants are not randomly chosen, results may be biased.
Sampling Opportunities in Research
Other Types of Sampling Methods in Psychology
Psychologists use various sampling techniques to improve the validity and reliability of their research. The five main types are:
- Opportunity Sampling – Selecting participants based on availability.
- Random Sampling – Every individual in the target population has an equal chance of being selected.
- Stratified Sampling – Participants are selected based on proportional representation from subgroups.
- Systematic Sampling – Selecting every nth person from a list.
- Volunteer Sampling – Participants actively sign up for the study.
Opportunity Sampling vs. Convenience Sampling
The terms opportunity sampling and convenience sampling are often used interchangeably. However, some researchers distinguish between them:
- Opportunity sampling refers specifically to selecting participants who are available at the time of the study.
- Convenience sampling is broader, including any method where participants are recruited based on ease of access.
Advantages and Disadvantages of Opportunity Sampling
| Advantages | Disadvantages |
|---|---|
| Quick and cost-effective | Prone to researcher bias |
| Easy to conduct in natural settings | May not be representative of the population |
| Useful for pilot studies | Increases risk of demand characteristics |
Relevant AQA A-Level Exam Questions
Q1: Explain how the sample of 10 participants could have been obtained from the students at the school using stratified sampling. (4 marks)
AO1 (2 Marks):
Stratified sampling involves dividing the target population into subgroups (strata) based on relevant characteristics and selecting participants proportionally.
AO2 (2 Marks - Application to the Study):
- The school consists of 500 students (100 per year group).
- The researcher should identify relevant subgroups (e.g., year groups).
- The number of students selected from each year should be proportional to the total number of students.
- Participants should then be randomly selected from each year group to ensure fairness.
Q2: Explain how the psychologist could have used random sampling to select the students in the follow-up study. (3 marks)
AO1 (3 Marks - Process of Random Sampling):
- The psychologist would create a list of all eligible students at the university.
- Each student would be assigned a number.
- A computer-generated random number system or lottery method would be used to select 20 students without bias.
Q3: Explain one problem with using random sampling in the follow-up study. (2 marks)
AO3 (2 Marks - Evaluation of Random Sampling):
- Time-consuming: It may take longer to contact randomly selected students and gain their consent.
- Risk of non-participation: Some selected students might decline, requiring additional selections.
Q4: Your psychology teacher asks you to design a study to investigate the correlation between time spent swimming and anxiety levels. Explain how a sample of 20 participants could be selected using stratified sampling and outline one strength of this method. (4 marks)
AO1 (2 Marks - Stratified Sampling Process):
- Identify relevant subgroups (e.g., gender, age, prior swimming experience).
- Calculate the proportion of participants needed from each subgroup.
- Randomly select participants from each subgroup to match population proportions.
AO3 (2 Marks - Strength of Stratified Sampling):
- More representative: Ensures different subgroups are included, improving generalisability.
- Reduces selection bias: Unlike opportunity sampling, it minimises researcher influence on participant selection.
Final Thoughts
Sampling opportunities in research impact the reliability and generalisability of findings. While opportunity sampling is convenient, methods like random and stratified sampling provide more representative results.
For psychology students preparing for AQA A-Level exams, mastering different sampling methods and their strengths/limitations is crucial for achieving high marks in research methods questions.