Experimental Design Flashcards
Define the key term ‘Experimental Design’.
The different ways in which testing of PPs can be organised in an experiment.
Define the key term ‘Independent Groups Design’.
PPs are allocated to different groups, where each group represents 1 experimental condition.
Define the key term ‘Repeated Measures’.
All participants take part in all conditions of the experiment.
Define the key term ‘Matched Pairs Design’.
Pairs of participants are matched on a variable that may affect the DV.
Then one participant is put into Condition A, the other into Condition B.
Define the key term ‘Random Allocation’.
A way of controlling participant variables in an IGs design, ensuring every participant is equally likely to be placed in each condition of the experiment.
Define the key term ‘Counterbalancing’.
A way of controlling the effects of order in a RMs design, where 50% of PPs experience conditions in one order, and the other 50% of PPs experience conditions in the reverse order.
How would you allocate participants in an Independent Groups Design?
Place half into Condition A and half into Condition B.
How would you allocate participants in a Repeated Measures Design?
Put all participants through Condition A first, and then Condition B later on.
How would you allocate participants in a Matched Pairs Design?
Match pairs based on IQ.
Put 1 into Condition A and the other into Condition B.
Evaluate the Independent Groups design.
Benefits:
• PP less likely to guess aims of study - reduced demand characteristics
• Order effects aren’t a problem
Negatives:
• PP in the different groups aren’t the same - differences in DV may be due to individual differences, not changes in the IV
• Less economic than repeated measures - each PP gives only 1 result. 2x as many PP would be needed for IG than RM to produce the same amount of data
Evaluate the Repeated Measures design.
Benefits:
• Control over PP variables
• Less PP needed so more economical
Negatives:
• Order effects - each PP does at least 2 tasks
e.g. drinking energy drink first can have a continuing effect when drinking water afterwards
• Order effects arise bc repeating 2 tasks could create boredom and thus deterioration in the second performance
• Order effects could cause performance to improve e.g. on skill-based tasks
• More likely PP will work out aim of study when experiencing all conditions of experiment - higher chance of demand characteristics
Evaluate the Matched Pairs design.
Benefits:
• PP take part in only 1 condition so order effects + demand characteristics aren’t a problem
Disadvantages:
• PP aren’t matched exactly - there may still be important differences which would affect the DV
• Matching is time-consuming and expensive - least economical
