RM: Experimental design

• What are the two main types of variables in an experiment?

  Independent variable (IV) and dependent variable (DV)
• Why is a comparison condition necessary in an experiment?

  To determine whether the IV affects the DV
• In the sleep experiment, what are the two levels of the IV?


  Sleep eight hours or more and sleep less than eight hours
• What are the two levels of the IV in the TV homework experiment?


  TV on and TV off
• What is experimental design?


  • The way the levels of the IV are delivered
  • It controls the influence of factors such as participant variables
• What are the limitations of repeated measures design?


  1. Order effects may affect performance
  2. Participants may guess the purpose of the experiment
• What is an order effect in a repeated measures design?


  An extraneous variable arising from the order in which conditions are presented
• How can researchers reduce practice effects in repeated measures design?


  By using two different but equivalent tests
• What is counterbalancing?


  An experimental technique used to overcome order effects in repeated measures design
• What are the two ways to counterbalance order effects?


  1. AB or BA groups
  2. ABBA method
• In the AB or BA method, how are participants divided?


  Into two groups where one group does A then B, and the other does B then A
• What is the ABBA method in counterbalancing?


  All participants take part in each condition twice in a specific order
• What is a matched pairs design?


  Pairs of participants matched on key variables, with each member allocated to different conditions
• What is random allocation in experimental design?


  Allocating participants to experimental groups using random techniques
• What are the key terms related to experimental design?

  • Counterbalancing
  • Experimental design
  • Independent groups design
  • Order effect
  • Random allocation
  • Repeated measures design
• How can you identify the experimental design used in a study?


  By determining if findings are analyzed by comparing scores from the same person or different groups
• What is the purpose of the cover story in an experiment?


  To prevent participants from guessing the aims of the study
• In a study comparing boys and girls, what type of experimental design is used?

  Independent groups design
• What type of experimental design is used when testing hamsters of different genetic strains?

  Independent groups design
• What experimental design is used when measuring reaction time before and after training?

  Repeated measures design
• In a study where students are paired based on GCSE grades, what type of design is used?


  Matched pairs design
• What type of experimental design is used when three groups are given different word lists to remember?


  Independent groups design
• What is one limitation of using a matched pairs design?

  It can be difficult to find perfectly matched pairs
• What is one strength of using a repeated measures design?

  It controls for participant variables
• What is one limitation of using an independent groups design?

  The researcher cannot control the effects of participant variables
• What is one strength of using an independent groups design?


  It avoids order effects
• What is one limitation of using a repeated measures design?


  Order effects may influence the results
• What is one strength of using a matched pairs design?

  It reduces participant variables