Psychology G544 Experimental Designs

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  • Created by: Maegan
  • Created on: 07-01-13 16:24

Independent Measures Design

- Each participant is in just one group


  • Each participant only experiences one condition > stop them from guessing what the study is about (reduces demand char)
  • Participants drop out can easily find someone else 


  • Need twice as many participants then repeated measures
  • Does not always adequately control for participant variables > researcher may end up with participants in one group who are all somehow 'naturally' better at the DV than the participants in the other group e.g. more intelligent, more suited to condition etc. This will skew results
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Repeated Measures Design

- Each of the participants will take part in both conditions


  • This controls participant variables because the participant variables in condition A are the same as condition B
  • Can recruit half the number of participants you would for other designs. 


  • Introduces another set of situational variables > doing one condition first may affect performance in the other condition. Can be due to either fatigue effects (participants - tired/bored) or practice effects (participant may improve second time - know what to expect). Means additional remedies might need to be built into experiment such as counterbalancing (some participants do A then B; the others do B then A)
  • Participant experience both conditions > may know what to expect
  • May have to create two different versions of the same task e.g. participants don't remember answers from the first time > make sure tasks have equivalent difficulty etc...
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Matched Pairs Design

Match the participants in each group for important participant variables which might extraneously affect the DV


  • Participant variables are controlled for because they are matched across conditions
  • No problems with order effects


  • If one participant drops out > have to find another 'match' or risk losing two sets of data
  • Can require hard work to match participants, especially on characteristics like IQ which need testing
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