Validity The degree to which an assessment, test or operationalised variable measures (a) what is intended, as opposed to (b) what is not intended, or (c) what is unsystematic or unstable. psychlotron.org.uk

Validity Internal validity The extent to which the study successfully measured what was intended External validity The extent to which the results of an investigation may be generalised beyond the research sample and situation psychlotron.org.uk

Internal Validity Chiefly determined by: Whether variables are operationalised in a suitable way Whether extraneous variables are adequately controlled Whether factors known to affect PP behaviour (researcher effects, demand characteristics) are minimised or eliminated psychlotron.org.uk

External Validity Chiefly determined by: Whether a sample is selected that is representative of the target population Whether the research environment (setting) and tasks used sufficiently resemble those that occur in PPs’ natural environments (mundane realism & ecological validity) psychlotron.org.uk

Social Influence: Internal Asch, Sherif Estimation tasks used (realism?); situational cues (e.g. multiple questions – demand characteristics?) Zimbardo Use of role play, mock environment (realism?) Milgram Outrageous situation – were PPs really fooled (demand characteristics?) psychlotron.org.uk

Social Influence: External Samples Tendency to rely on US students (predominantly young, middle class, white males BUT not always e.g. X-cultural studies) Settings Often lab-based & slightly bizarre (lacking in realism BUT remember Hofling, Bickman and some Milgram studies) psychlotron.org.uk