experimental designs

• what is an experimental design 


  different ways we can organise participants in relation to the experimental design
• what are the types of experimental designs 


  independent groups , repeated measures, matched pairs,
• what is an independent group 


  two separate groups of participants experience two different conditions of the experiment
• Participants who occupy the different groups are not the same in terms of participant variables ( characteristics of other people- whether they're chatty or not).
• What is random allocation

  it reduces researcher bias - e.g putting the names of participants into a hat and pulling them out at random
• What are strengths of independent groups 


  Order effects are not an issue

  Participants are less likely to guess the aim of the investigation
• What are the limitations of independent groups 


  Less economic - each participant contributes a single result

  More expensive - as you need to double the amount of participants needed for an equivalent result
• What are repeated measures


  all participants experience both conditions, 2 mean scores from both conditions would be compared to identify differences
• What are limitations of repeated measures

  Order effects - participants are going to guess what is going on , as they have more familiarity, you deal with this by counter balancing

  Order effects - repeating a task twice could create boredom which could cause deterioration in performance, acting as a cofounding variable
• What is counter balancing 


  Half of the participants so they experience the conditions in one order
• Why do we use counter balancing 


  to negate away from order effects
• What are matched pairs 


  Participants are paired together on a variable relevant to the experiment- you do something before getting paired - and its an attempt to control the cofounding variable
• What are advantages of matched pairs 


  attempts to control the cofounding variable - so yk you’re IV affects the DV

  Participants only in one condition so order effects and demand characteristics are less
• what is a limitation of matched pairs 


  Time consuming and expensive-doing a pre test before you get to the investigation also is less economical