Experimental Designs Flashcards
(9 cards)
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
