Control of Variables

• EVs - 'nuisance' variables that affect the relationship between the IV and DV and can usually be controlled before the study starts
• Confounding variables - variables that vary systematically with the IV so we cannot be sure what caused the change in the DV (e.g. gender/age)
• Demand characteristics - pps interpret cues from the experimenter (investigator effects) and research situation which can change their behaviour
• Randomisation - the use of chance to reduce the researcher's influence on the design of the investagtion
• Standardisation - making sure that all pps are subjected to the same instructions and experience