Experimental designs

Independent measure design- Different participants are placed in each condition i.e. there are two separate and different groups.

Repeated measure design- The same participants are used in both conditions (experimental and control conditions) i.e. each person takes part twice.

Matched pair design- Different participants are used in each condition but they are matched on key variables to form “pairs” (to imitate repeated measures)

Strengths-
-No issue of order effect.
-Participants are less likely to guess the aim of the study.

Weaknesses-
-Individual differences.
-No control on participant variables.
-Twice as many participants needed therefore high cost.

Strengths-
-Individual differences are removed and therefore can compare “like to like”

Weaknesses-
-The DV could be affected by confounding variables rather than the IV.
-Suffers from order effect I.e doing 2 tasks can lead to fatigue or boredom and effect the performance task. However, this can be minimised with counter balancing.
-Participants can guess the aim of the study so demand characteristics can effect the outcome of the study.

Strengths-
-It reduces participants orde effect so counter balancing is not necessary.

Weaknesses-
-Time consuming to match the pairs of participants for each condition.
-It would require a pilot study which is a reliable and valid procedure to pre-test participants to obtain matched pairs.