Controlling variables

Extraneous variables= any variable other than the iv which may affect the dv

Confounding variables= a variable that has actively affected the dv other than the iv.

Situational variables= aspects of situation or environment which may affect participants behaviour in an experiment.Each group should complete experiment in the same situational condition.

Investigator effects= researcher unconsciously influences results. Write standardised instructions so the researcher can’t influence participants while explaining the experiment.

Participant variables= individual characteristics of participants affect their behaviour. Repeated measures or matched pairs design.

Standardisation = making things exactly the same in all conditions

Random allocation= eg 20ppts … all names put into hat… one name picked out and put in one and the next name put in 2 and repeat

Counterbalancing = abba… one group does repeated measures a then b and other group does repeated measures b then a.

Randomisation=controlling variables my means of chance eg randomise word order in list.