Variables

• extraneous variables

  - any variable other than the IV that could influence the measurement of the DV

  - potentially shows a casual relationship between IV and DV that isn't really there, or can hide one
• participant variables

  - in an IGD if there are more ppl with relevant characteristics, prior knowledge/skills related to the task in 1 condition

  - can result in a difference in performance between conditions, unrelated to IV
• situational variables

  - environmental factors present in 1 condition but not the other, which can result in a change in behaviour between them

  - eg: temperature, noise, visual differences
• order effects

  - in RMD, the fact the ppt has already completed one condition can alter behaviour in the second condition

  - practice effects, fatigue; improving/worsening performance
• confounding variables

  - a variable other than the IV that changes systematically between the levels of IV

  - as you change the IV, you also change the confounding variable; researcher then measures effect of CV as well as IV
• ways to control these variables

  - ppt variables: random allocation of ppts/randomisation of instruction (eg: random word list), matched pairs

  - order effects: counter-balancing

  - situational variables: standardised procedures

  - demand characteristics: single and double blind trials
• peer review

  - before publication, researcher needs to show their study to other experts in the field

  - unaccounted for variables may be identified which have confounded the results, lacks internal validity
• pilot studies

  -a small-scale version of the main research study conducted before the main study

  - uses same methodology, data collection/analysis to identify any issues within the procedure and methods