Experimental designs

• What are the three experimental designs?

  • Independent groups
  • Repeated Measures
  • Matched pairs
• What is the Independent group design?

  Participants in each condition are different
• What is the repeated measures design?

  All participants take part in every condition
• What is matched pairs design?

  Similar participants are paired on participant variables then split into either condition A or B
• Evaluation of Independent groups design:

  -Participant variables not controlled (results may not be down to IV)

  +No order effects (participants less likely to guess aim)

  • How to improve = Use random allocation
• Evaluation of repeated measures design:

  -Order effects (participants could become more accustomed so improve or become fatigued so do worse)

  -Demand Characteristics (participants guess the aim of study)

  +Participant variables controlled

  +Fewer participants needed

  • How to improve = Counterbalancing
• Evaluation of matched pairs design:

  +Fewer demand characteristics

  +Fewer participant variables

  -Participants can never be matched perfectly

  -Time consuming to match participants