experimental design

• independent groups 


  participants are allocated to different groups where each group represents on experiemental condition
• repeated measures

  all participants take part in all conditions of the experiment
• matched pairs design 


  participants matched on some variables that may affect the. then one member is assigned condition A and the other condition B
• random allocation 


  each participant has the same chance of being in one condition as any other
• counterbalancing 


  attempt to control for the effects of order in a repeated measures design. half participants do conditions in on order and the other half in the opposite order
• independent groups (evaluation) 


  weakness: participants in each groups are not the same + less economical than repeated measures

  strength: order effects are not a problem + participants are less likely to guess the aim
• repeated measures (evaluation) 


  weakness: each participant has to do at least two tasks (could get tired or bored)

  strengths: fewer participants needed + variables are controlled
• matched pairs 


  weakness: participants can never be matched exactly + time consuming + expensive

  strengths: order effects and demand characteristics are less of a problem