experimental/research designs Flashcards
What are the types of experimental design?
- repeated measures
- independent groups
- matched pairs
What is repeated measures?
when ppts take part in all conditions/all levels of the IV
What are the strengths for repeated measures?
- stops ppts variable
- fewer ppts - economical benefits
What are limitations for repeated measures?
- order effects (the order of conditions may affect performance)
- ppts may get bored + tired
- allows the ppts to work out the aim of the study - may affect the DV measurement
How do you overcome the limitations (order effects) for repeated measures?
use counterbalancing - ensures that each condition in a repeated measures design is tested first or second in equal amounts
What is independent groups?
ppts only take part in one condition
What are strengths for independent groups?
no order effects
What are limitations for independent groups?
the natural variation between the individuals’ abilities and/or characteristics (ppt variables) in each group may affect the DV measurements
How do you overcome the limitations for independent groups?
random allocations - randomly allocate ppts to conditions which (theoretically) distributes ppts variables evenly
What is matched pairs?
collect ppts, find a second group that match on characteristics, then treat as independent groups
What are strengths for matched pairs?
- reduced order effects
- differences between the two groups are minimised
What are limitations for matched pairs?
- time consuming
- an exact match is rarely possible
- not possible to control all ppts variable
How do you overcome the limitations for matched pairs?
- use few ‘matched’ characteristics (restrict the number of variables to match on to make it easier)
- conduct a pilot study to consider key variables
