Education

Discover what operationalisation means in psychology and how to define variables and hypotheses in measurable terms with clear A-level examples.

Learn what reliability means in psychology, the four main types — test–retest, inter-rater, internal, and external — plus how psychologists test and improve consistent results.

Discover the four main types of validity in psychology — internal, external, construct, and criterion validity — with clear examples and how to improve each for valid research.

Ecological validity in psychology refers to how well research results apply to real-world settings. Learn its definition, importance, examples, and how to improve it.

Investigator effects occur when a researcher’s behaviour or expectations influence participants. Discover how to control them using double-blind designs, standardisation, and randomisation.

Demand characteristics occur when participants guess a study’s purpose and change their behaviour. Learn what they are, examples, and how psychologists control them.

Extraneous and confounding variables can distort results in psychological research. Learn their types, examples, and how to control them for reliable, valid experiments.

Standardisation in psychology ensures every participant experiences the same procedures, instructions, and conditions — making experiments fair, reliable, and valid. This guide explains what standardisation means, the four main types, and why it’s essential in A-level Psychology research methods, with clear examples and exam-style answers.

Understanding experimental designs in psychology helps researchers and students test ideas scientifically. This guide explains the four main designs — independent, repeated measures, matched pairs, and quasi — with examples, strengths, and weaknesses. Perfect for A-level revision or anyone learning how psychologists structure their experiments.