control of variables Flashcards
what are extraneous variables (2)
-variables other than the IV which affects the DV if it isn’t well-controlled
-they make it harder to detect a result- they don’t vary systematically with the IV
what are confounding variables (3)
-variables other than the IV which affects the DV if it isn’t well-controlled
-changes systematically with the IV
-becomes difficult to be sure of the origin of the impact of the DV
eg. memory test done at different times of the day- should be done tat the same time
what are demand characteristics (3)
-a cue from researcher/situation which may allow participants to guess the aim of the study
-causes behaviour to change from how they would usually act- participant reactivity
-please you and screw you effect- affects validity of results
what are investigator effects (2)
-effects of the researchers behaviour on the DV
-eg. design of study, selection of participants, interactions with participants
what is randomisation (3)
using chance to reduce the effects of bias from investigator effects
-minimises effects of extraneous/confounding variables
eg.memory test for recalliing order of words on list should be randomly generated
what is standardisation (2)
-using the exact same procedures, environment and instructions for all participants
-eliminates non standardised instructions as extraneous variables
what is single blind procedure (3)
-researches dont tell participants the aims/conditions
-used to ensure participants dont bias the results
-avoids demand characteristics
what is double blind procedure (2)
-neither participants nor researcher knows the aims
-prevents bias in results due to demand characteristics or placebo effect
what are control groups (2)
-used to set a baseline to compare results from the experimental condition
-if theres a significant change in experimental condition compared to control group we can be more sure it was the effect of the IV
what are pilot studies
small scale versions of a study done before the real study to identify potential problems so they can be dealt with
what are 4 potential problems of pilot studies
extraneous variables
confusing instructions
p’s showing demand characteristics
behavioural categories not operationalised
4 examples of extraneous variables
participant variables
demand characteristics
situational variables
order effects
how to control for participant variables
-matched pairs design
how to control for order effects
counterbalancing (ABBA format)
how to control for situational variables
standardisation (making sure p’s have same experience)
how to control for demand characteristics (2)
-single/double blind trial
-double blind trial stops investigator effects
