Experimental designs

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    Created by
    Alexandru Chiriac

    Cards (9)

    • Repeated measures design:
      • Each participant takes part in every condition under test.
      • Each condition represents one level of the Independent variable
      • there may also be a control condition
    • independent measures design:
      • Participants are allocated to two (or more) experimental groups representing different levels of the IV.
      • There may also be a control group
    • Matched participants design:
      • Participants who are similar on key variables (eg memory ability, age) are paired. One member of the pair is placed in group A and the others in group B.
      • This means there are two groups of participants. Each group is given one level of the IV.
    • Positive of Repeated measures:
      + Good control of participant variables , since same person is tested twice.
      + Fewer participants needed than in the independent measures design.
    • Negative of repeated measures:
      - Practice effect. Student may be better and had adapted from the first condition.
      - Participants may guess the purpose of the experiment.
      - condition A may be easier than condition B
    • Independent measure positives:
      • Avoids order effects because each participant is only tested once.
      • Avoids participants guessing the aims of the experiment
    • Negatives of Independent measures design:
      - No control of participant variables. Participants in group A may be more intelligent that is why group A had higher on the test than group B.
      - Needs more participants than repeated measures design. If there is 20, they will be split between the two groups. And collect data only for 10 people.
    • matched participants positive:
      + Acts as a control for participant variables because of the matching (like repeated measures)
      + Avoids order effects because it is like an independent measures design.
    • Matched participants negative:
      - Very time consuming to match participants on key variables
      - May not control all participant variables because you can only match on variables known to be relevant, but it could be that other variables are important.
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