Experimental Designs Flashcards
what are independent measures?
- different ppts are used in each condition
- randomly allocated to give each ppt an equal chance
- lottery system, number generator
why do we use experimental designs?
to determine how we allocate ppts to conditions in an experiment
what are repeated measures?
using the same ppts for each condition
what are matched pairs?
pairing ppts based on a variable e.g age, then one member of the pair goes into eithercondition
what is counterbalancing?
- used to overcome the effects of a repeated measures designs
- ensures each condition is tested first or second in equal amounts
what are order effects?
EV’s that arise from the order conditions are presented, practice effects and fatigue effects
what are the strengths of independent measures?
- avoids order effects and the problems they cause
- avoids demand characteristics and ppts are only aware of one condition
what are the limitations of repeated measures?
- strong chance of order effects
- demand characteristics may occur
what are the limitations of independent measures?
- requires a larger number of ppts (time consuming and hard to recruit)
- cannot control for individual differences which could become EV’s
what are the strengths of matched pairs?
- reduced effect of individual differences
- avoids order effects and demand characteristics
what are the strengths of repeated measures?
- controls for individual differences
- fewer participants needed (saves time)
what are the limitations of matched pairs?
- nearly impossible
- requires a large number of ppts
EQ: how can we reduce extraneous variables?
test all ppts in the same room, make sure all ppts hear the same instructions, ensure all ppts are tested by the same researcher
