How do psychologists sample participants, act ethically, and make studies trustworthy?
Sampling, ethics, reliability and validity: methods of sampling participants, the ethical issues and guidelines in psychological research, and the concepts of reliability and validity used to judge a study's quality.
The SQA Higher Psychology research content on sampling and quality: random, opportunity, self-selected and other sampling methods, the ethical issues and guidelines such as consent, deception and protection from harm, and the concepts of reliability and validity used to evaluate research.
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What this dot point is asking
This research content lets you judge how trustworthy and acceptable a study is. The SQA wants you to know the methods of selecting participants, the ethical issues and guidelines in psychological research, and the meaning of reliability and validity. These concepts are examined directly and are the language you use to evaluate every study in the course.
The answer
Sampling methods
Ethical issues and guidelines
Reliability
Validity
Examples in context
The classic studies are ideal for applying these concepts. Milgram's obedience study is highly reliable (it has been replicated with similar results) but is criticised on ethics (deception, lack of fully informed consent, psychological harm) and on ecological validity (an artificial laboratory task). Zimbardo's Stanford prison study is criticised on ethics and on internal validity, because the researcher's own involvement may have shaped the behaviour. Survey and correlational studies in the stress and relationships topics often use self-selected or opportunity samples, which limits how far they generalise, and rely on self-report, which can reduce validity. Using these examples to judge sampling, ethics and validity is exactly the evaluation the SQA rewards across the whole paper.
Try this
Q1. Explain the difference between random and opportunity sampling. [4 marks]
- Cue. Random sampling gives every member of the population an equal chance (less bias, more representative); opportunity sampling uses whoever is available (quick but biased).
Q2. Explain the difference between reliability and validity. [4 marks]
- Cue. Reliability is consistency (the same result on repeating); validity is accuracy (measuring what it claims and applying to real life). A study can be reliable without being valid.
Exam-style practice questions
Practice questions written in the style of SQA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
SQA Higher (research)6 marksDescribe two sampling methods and explain one strength of each.Show worked answer →
A -mark question testing research knowledge. Markers want accurate descriptions plus a relevant strength.
Two strong choices are random sampling (every member of the target population has an equal chance of selection, which reduces bias and improves representativeness) and opportunity sampling (using whoever is available and willing, which is quick, cheap and practical). Explaining why each strength matters, for example that random sampling supports generalisation while opportunity sampling makes a study feasible, secures the marks.
SQA Higher (research)8 marksExplain the main ethical issues a psychologist must consider when carrying out research.Show worked answer →
An -mark question. Markers reward developed explanation of several issues, not just a list of words.
Key issues are informed consent (participants should agree knowing what is involved), deception (should be avoided or justified and followed by a debrief), the right to withdraw (participants may leave at any time), protection from harm (no lasting physical or psychological damage), and confidentiality (data kept private). Linking each to how it protects participants, and noting that studies such as Milgram's breached several, raises the mark.
Related dot points
- Research methods and the experiment: the main research methods used in psychology, the experimental method, hypotheses and variables, experimental designs, and the strengths and weaknesses of each method.
The SQA Higher Psychology research content on methods: the experimental, observation, survey, case study and correlational methods, the structure of an experiment including hypotheses and independent and dependent variables, experimental designs, and the strengths and weaknesses of each approach.
- Analysing and presenting data: qualitative and quantitative data, descriptive statistics including measures of central tendency and dispersion, methods of presenting data, and drawing conclusions from research findings.
The SQA Higher Psychology research content on data: the difference between qualitative and quantitative data, descriptive statistics such as the mean, median, mode and range, methods of presenting data in tables and graphs, and how psychologists draw and justify conclusions from findings.
- The Higher Psychology assignment: an overview of the researched report worth 40 marks, including the research question, the use of research methods, the analysis of findings, and the conclusions and evaluation.
An overview of the SQA Higher Psychology assignment: the 40-mark researched report in which a candidate plans a research question, gathers and analyses information using research methods, presents findings, and draws and evaluates conclusions under controlled conditions.
- Conformity and obedience: the nature of conformity and obedience, explanations of why people conform and obey, factors that affect them, and the key research evidence and methods used to study social influence.
The SQA Higher Psychology mandatory Social Behaviour topic on conformity and obedience: types and explanations of conformity, explanations of obedience, the factors that increase or reduce social influence, and the key research evidence and methods including Asch, Milgram and Zimbardo.
Sources & how we know this
- SQA Higher Psychology Course Specification — SQA (2019)
- SQA Higher Psychology: guidance on creating assessments — SQA (2019)