Experimental design

• Experimental design

  It refers to how the participants that are taking part in a study are allocated to conditions (which of group are they put into)
• Independent group

  Two separate groups of participants take part in two different conditions of the experiment

  If there's 2 levels of IV, only 1 group will experience it and there will be a control group.

  The two groups can the be compared.
• Repeated measures

  Both groups experience the conditions of the experiment. The participants will be tested on one condition but then later by a different condition.

  2 sets of data will be compared to identify difference comparing the effect
• Matched pairs

  Participants are paired together on variable/variables relevant to the experiment 

  Then one participant would be allocated to a different condition, so there is control over confounding variables of participant variables.
• Independent group advantages

  • Order effects are not a problem 
  • Less chance of guessing the aim and changing their behaviour (demand characteristics)
• Independent group disadvantages

  Less economical 

  • participants who occupy the different group designs are not the same

  Individual differences may affect the dependent variable (your abilities)
• Independent group solution

  To deal with it, they could use random allocator.
• Repeated measure design advantages

  Same participants are used, meaning participant variables are reduced

  • Individual differences would not occur as it is the same person
• Repeated measure design disadvantages

  Order effects are a problem

  Demand characteristics 

  • Each participant has to do at least two tasks and the order of the tasks may be significant
• Repeated measure design solutions

  • Counterbalancing- half take part A and the other take part B. 
  • Control order effects