A variable in a study which is not the IV but which also affects the DV.
Demand characteristics
A cue that makes participants unconsciously aware of the aims of a study or causes them to change their behaviour to match what they think is expected.
Extraneous variable
Any variable, other than the IV, which may affect the DV and therefore affect validity of the findings. Extraneous variables need to be controlled in an experiment wherever possible.
Interviewer bias
The effect of an interviewer’s expectations, communicated unconsciously, on a respondent’s behaviour.
Investigator effect
Anything that an investigator does that affects a participants’ performance in a study, directly (through interaction with the participant) or indirectly (through bias in the study design).
Standardised procedure/ Standardisation
A set of procedures that are the same for all participants in order to be able to repeat the study.
