Lesson 3: Experimental design

• What are the two main groups in experimental designs?

  Experimental and control conditions
• What does repeated measures involve in experimental design?

  Using the same participants in each condition
• What are the strengths of repeated measures design?

  • Controls participant variables
  • More economical than other designs
• How does repeated measures control participant variables?

  Participants take part in both conditions
• Why is repeated measures considered more valid?

  Differences are due to the effect of IV
• Why is repeated measures more economical?

  No additional cost for more participants
• What are the weaknesses of repeated measures design?

  • Demand characteristics likely to occur
  • Order effects can be experienced
• What are demand characteristics in repeated measures?

  Participants become aware of the study's aim
• How do order effects impact repeated measures?

  Participants may become tired or bored
• How can order effects be controlled in repeated measures?

  Through counterbalancing the order of conditions
• What is the independent groups design in experiments?

  Using different participants in each condition
• What are the strengths of independent groups design?

  • Less chance of demand characteristics
  • Less chance of order effects
• Why are demand characteristics less likely in independent groups?

  Participants only take part in one condition
• How does independent groups reduce order effects?

  Participants only take part in one condition
• What are the weaknesses of independent groups design?

  • Participant variables are not controlled
  • Less economical than repeated measures
• Why are participant variables a concern in independent groups?

  Different participants may have individual differences
• Why is independent groups less economical?

  Requires twice as many participants
• What is the matched pairs design in experiments?

  • Different participants in each condition
  • Matched on important variables
• What are the strengths of matched pairs design?

  • Less chance of demand characteristics
  • Less chance of order effects
• Why is matched pairs rarely used?

  It is less economical than other designs
• What is a challenge of matched pairs design?

  It is difficult and time-consuming to achieve