Experimental Designs Flashcards
Experimental design
The different ways pps can be organised in relation to the experimental conditions
Independent groups
Pps are allocated to different group where each group represents 1 experimental condition - the experiment v control for example
AO3 of Independent groups
LIMITATION
- Pps in diff groups may not be the same => diff in groups may be due to pp variables => instead random allocation
- Less economical than repeated measures as 2x as many pps needed
STRENGTH
- Order effects aren’t a problem as pps only do 1 condition
Repeated Measures
All pps take places in all conditions of the experiment and results from each are compared
AO3 of Repeated Measures
LIMITATION
- Order of task may be significant => dealt with by counterbalancing
- Repeating 2 tasks may: create boredom or fatigue causing deterioration in performance / improvement due to practice
- Demand characteristics as pps figure out aim of study
STRENGTH - Pp variables are controlled (higher validity) + less pps needed
Matched Pair Design
Pairs of pps are first matched on a variable that may affect the dependent variable => 1 assigned to condition A, the other B
=> an attempt to control the CV of pp variable + often a pre test is needed for effective matching
AO3 of Matched Pairs
LIMITATION
- Pps can never be matched exactly even identical twins
- Matching is time consuming + expensive - less economical
STRENGTH - only taking part in 1 condition so order effects + demand characteristics are less of a problem
Random allocation
An attempt to control pp variables in independent group design
=> ensures each pp has same chance of being in 1 condition as any other
Counterbalancing
An attempt to control the order effects in a repeated measure design
=> 1/2 pp experience a condition in 1 order, the other in opposite order
