IV manipulated, participants randomly allocated, other variables controlled.
Quasi-experiment
Groups based on an existing characteristic (e.g. gender), so no random allocation.
Natural experiment
IV varies naturally; the researcher does not manipulate it.
Designs: independent samples (different people in each condition; risk of participant variables), repeated measures (same people; risk of order effects, controlled by counterbalancing), matched pairs.
The full notes, worked example and check questions for this subtopic are in the app.
Exam tip: Practise operationalizing: 'memory' becomes 'number of words correctly recalled from a list of 20 within 2 minutes'.
M.2Qualitative methods
Key terms
Semi-structured interview
Prepared questions with flexibility to follow up answers.
Case study
An in-depth study of an individual, group or event using several methods.
Triangulation
Using several methods, researchers or sources to check credibility.
Reflexivity
Researchers reflect on how their own biases may affect the research.
Qualitative research gathers rich, detailed data about meanings and experiences (interviews, focus groups, observations, case studies).
The full notes, worked example and check questions for this subtopic are in the app.
Exam tip: Use the word 'credibility' for qualitative studies and give a concrete way it was increased.
M.3Sampling and generalization
Key terms
Random sample
Every member of the target population has an equal chance of being chosen.
Opportunity sample
Whoever is available at the time.
Self-selected (volunteer) sample
Participants put themselves forward.
Purposive sample
Participants chosen because they have specific characteristics (common in qualitative research).
Snowball sample
Participants recruit others; useful for hard-to-reach groups.
Representative samples allow generalization to the target population; biased samples limit it.
The full notes, worked example and check questions for this subtopic are in the app.
Exam tip: Name the sampling technique, then link it to the population the results can (and cannot) be generalized to.
M.4Data analysis
Key terms
Mean, median, mode
Measures of central tendency.
Standard deviation (SD)
Average spread of scores around the mean.
Correlation coefficient (r)
Strength and direction of a linear relationship, from −1 to +1.
Statistical significance
Results unlikely to be due to chance, usually p < 0.05.
Effect size
How large a difference or relationship is, e.g. Cohen's d.
In a normal distribution about 68% of scores lie within 1 SD of the mean and about 95% within 2 SD.
The full notes, worked example, interactive diagram and check questions for this subtopic are in the app.
Exam tip: State both direction and strength of a correlation (e.g. 'a strong negative correlation, r = −0.78') and say it does not show cause.
M.5Research ethics and the research proposal
Key terms
Research proposal
A planned investigation with a focused question, justified method, sampling, ethics and data analysis plan.
Pilot study
A small trial run to check procedures and materials.
Operationalized hypothesis
A testable prediction with measurable variables.
A good research question is focused, linked to theory and feasible. The hypothesis should be operationalized.
The full notes, worked example and check questions for this subtopic are in the app.
Exam tip: Check your hypothesis states both conditions of the IV and exactly how the DV is measured.