Experimental design

• Independent groups

  two or more separate groups experience different conditions.

  +more than one experimental condition, no order effects, participants less likely to guess the aim.

  -less economical, need more participants, random allocation.
• Repeated measures

  Each participant would experience both conditions.

  Use counterbalancing= to control effects of order, half experience condition 1 first, the other half experience condition 2 first.

  +participant variables are controlled, fewer participants needed.

  -order effects= practice, boredom, fatigue, demand characteristics.
• Matched pairs

  Participants are matched on a number of variables that may affect the dependent variable, but only tested once.

  +participants only take part in 1 condition so no order effects or demand characteristics.

  -participants can never be perfectly matched, matching pairs is time consuming and expensive.