Designs

• Matched Pairs Design (MPD)

  • 2 groups, each participant is matched in each group
  • Strengths:
  • Controls participant variables
  • Researcher sure DV is due to IV manipulation not characteristics
  • Avoids order effects; only tests once
  • Weaknesses:
  • Time-consuming
  • Limited funding may make it impractical
  • May not control all participant variables; only known relevant variables matched
  • Controlling Weaknesses: Start with large participant group to ensure you can obtain matched pairs on key variables
• Independent Measures Design (IMD)

  • Different participants in two (or more) experimental groups for each IV level
  • Maybe control that experiences no IV change but still measured for DV to see if change without intervention
  • Strengths:
  • No order effects; only tests once
  • Prevents them guessing aims
  • Weaknesses:
  • No participant variable control
  • Characteristics may affect performance
  • Needs larger sample
  • Controlling Weaknesses; randomisation
  • Random group allocation
  • Should have pretty balanced characteristics
  • No types clustering
• Repeated Measures Design (RMD)

  • Each participant takes part in every tested condition, 1 IV level
  • Maybe control condition experiences no IV change
  • Strengths
  • Control participant variables
  • Same person tested twice
  • Fewer participants needed
  • Has larger sample
  • More dependable results
  • Weaknesses
  • Order effects:
  • Better performance on 2nd; experience (practice effect)
  • Worse performance on 2nd; bored or tired (fatigue effect)
  • Participants may guess purpose doing both conditions
  • Controlling Weaknesses; counterbalancing
  • Change condition order so each is tested first and second equally