Please enable JavaScript.
Coggle requires JavaScript to display documents.
Control of variables - Coggle Diagram
Control of variables
- only thing which should influence the DV is the IV.
- any other variables may potentially interfere with the IV (or DV) & should be controlled/removed
- additional unwanted variables are called extraneous variables
- they're usually identified by research at beginning of research by researcher who then takes steps to minimise their influence
- most EV are straightforward to control, e.g. age off ppts, lighting in lab etc.
- these are describes as 'nuisance variables' which don't vary systematically with the IV
- they may 'muddy' the experimental water but do not confound the findings of the study
- they may make it harder to detect a result
- confounding variables do vary systematically with the IV
- personality = confounding variable
- any variable other than the IV which may have effected the DV so we cannot be sure of the true source of changes to the DV
- = the use of chance whenever possible to reduce researcher's influence on the design of the investigation
- it's an attempt to control investigator effects, e.g. memory exp may involve ppts recalling words from a list. order of list should be randomly generated so position of each word isn't decided by the experimenter
- where ppts are involved in no. of conditions, order of conditions should be randomly determined
- if ppts were to take part in all conditions, order in which conditions were completed would need to be randomised for each ppt
- ppts = not passive & will spend much time trying to make sense of a new situations they find themselves in
- participant reactivity = significant EV in experimental research & is one which is very difficult to control
- certain clues help ppts interpret whats going on
- these clues (or cues) are the demand characteristics of the experimental situation & may help ppts to 'second-guess' the experimenter's intentions as well as the aims of the study
- ppts may look for clues telling them how to behave in certain situation
- they may act in way they think they're expected to & over-perform to please the experimenter (the 'please-U effect')
- or they may deliberately under-perform to sabotage the result of the study (the 'screw-U effect')
- ppts reactivity also leads to investigator effects
-
- as much as possible, ppts in an investigation should be subject so same env, info and experience
- to ensure this, all procedures are standardised
- Standardisation = using exactly yhe same formalised procedures and instructions for all ppts in a research study