Experimental designs

• What are experimental designs?

  Ways participants are organized in experiments
• What is the independent groups design?

  Different participants for each level of IV
• What are control and experimental groups?

  Groups used to compare effects of IV
• What is the repeated measures design?

  All participants take part in all IV levels
• What is the matched pairs design?

  Participants matched and assigned to conditions
• What is a case study?

  A detailed examination of an individual
• What are the strengths and weaknesses of independent groups design?

  Strengths:

  • No order effects
  • Fewer participants needed

  
  

  Weaknesses:

  • Different participants in each group
  • Participant variables can act as EVs
• What are the strengths and weaknesses of repeated measures design?

  Strengths:

  • No participant variables
  • Fewer participants needed

  
  

  Weaknesses:

  • Order effects reduce validity
  • Practice effect may occur
• What are the strengths and weaknesses of matched pairs design?

  Strengths:

  • No order effects
  • Fewer participant variables

  
  

  Weaknesses:

  • Time-consuming to match participants
  • Doesn't control all participant variables
• How can participant differences be dealt with in experiments?

  Using chance or systematic allocation methods
• What is counterbalancing in dealing with order effects?

  Half do conditions in one order, half in reverse
• What is observation of an individual in research?

  A researcher records data by watching participants
• Why may observation of an individual introduce EVs?

  Participants not randomly allocated to conditions
• What are the key differences between independent groups, repeated measures, and matched pairs designs?

  • Independent groups: Different participants for each condition
  • Repeated measures: Same participants for all conditions
  • Matched pairs: Participants matched and assigned to conditions