Experimental designs

experimental designs definition

the different ways in which participants can be organised in relation to the experimental condition

describe independent groups

is where all participants experience one level of the IV only- the the performance of 2 groups would be compared to create results

describe repeated measures

all participants experience both conditions of the experiment

describe matched pairs

participants are paired together on a variable or variables relevant to the experiment (IQ scores) as an effect to control participant variables

strengths of independent groups

-randomized so reduced risk of demand characteristics (acting unnaturally)

-more expensive

-higher internal validity

-avoid order effects (when order of IV effects result to another)

weaknesses of independent groups

-less comparable due to extraneous variables

-expensive

how to reduce error in order effects

ABBA method/counterbalancing

-one group do IV a the IV b and vice versa to reduce different response

strengths of repeated groups

-cheaper cost

-easily comparable results

weaknesses of repeated measures

-risk of demand characteristics (acting unnaturally)

-order effects

(can deal with limitations by hiding nature of question)

strengths of matched pairs

-easily comparable results

-avoid order effects

weaknesses of matched pairs

-expensive

-hard to find matches- so don’t match too many characteristics