1. Sampling

2. When we carry out research we need people to take part, these are called participants. It is important to use suitable participants in your study.
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3. The population is the group of people from whom the sample is drawn
The population is the group of people from whom the sample is drawn. For example if the sample of participants is taken from sixth form colleges in Leeds, the findings of the study can only be applied to that group of people and not all sixth form students in the UK and certainly not all people in the world.

4. Obviously it is not usually possible to test everyone in the target population so therefore psychologists use sampling techniques to choose people who are representative (typical) of the population as a whole. =
If your sample is representative then you can generalise the results of your study to the wider population.

5. Sampling Techniques
We will now examine some of the techniques used by Psychologists to obtain participants for their sample

6. Opportunity Sampling Common Room
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Want to be in my study?
Common Room
Opportunity sampling is the sampling technique most used by psychology students. It consists of taking the sample from people who are available at the time the study is carried out and fit the criteria you are looking for.

7. Random Sampling
This is a sampling technique which is defined as a sample in which every member of the population has an equal chance of being chosen. This involves identifying everyone in the target population and then selecting the number of participants you need in a way that gives everyone in the population an equal chance of being picked.

8. Stratified Sampling = 60% female 40% male = 60% female 40% male
Stratified sampling involves classifying the population into categories and then choosing a sample which consists of participants from each category in the same proportions as they are in the population.

9. Self-selected Sampling
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I’ve always wanted to be in a study….
Sounds rubbish…
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Psych Lab
Self selected sampling (or volunteer sampling) consists of participants becoming part of a study because they volunteer when asked or in response to an advert.

10. Home Work! Explain what is meant by a representative sample?
Explain why larger samples are not always more representative than smaller samples?
‘A target population and a sample can be made up of the same people’. True or False?

11. Examiners Hint!
If an exam question asks you to identify an ethical problem with a study then start your answer by actually identifying the problem by using the appropriate term, for example consent, confidentiality, etc. You then earn further marks by actually applying it to the study in question.

12. Ethics!
Give 2 examples of people who may not be able to give their consent in psychological research.
Explain how psychologists may sometimes justify deceiving their participants.
Describe how ethical guidelines help to promote the welfare of human participants.

13. Why are ethics important?
A number of reasons including:
Moral obligation to society
Professional values (‘amelioration of the human condition’)
Image of the discipline and profession
Practical reasons e.g. getting participants

14. What are the issues?
Research practices that threaten (directly or indirectly) the well-being of the participants e.g.:
Informed consent (lack of)
Deception
Risk of harm (physical/psychological)
Confidentiality & privacy (threats to)

15. Making ethical decisions
Where ethical problems arise, a cost-benefit analysis is often applied, where:
Costs are the (potentially) negative consequences of the research – usually for the PPs involved .
Benefits are the (potentially) positive consequences of the research for the PPs or (more usually) for society

16. Cost-benefit analysis
Provides a framework for making ethical decisions
Involves subjective judgments about costs and benefits
Consequences cannot always be anticipated e.g. Zimbardo, Milgram