Experimental design Flashcards
What is the experimental design?
How ppts are assigned to conditions in a study
What is the independent groups design?
Ppts only perform one condition of the IV
What is a strength of the independent groups design?
No order effects
Less likely to be DC as less likely to guess the aim
What is a limitation of the independent groups design?
No control over ppt effect- different abilities of ppts in various conditions can effect DV.
Need a lot of ppts
How can we improve the Independent groups design?
Random allocation- ensures each ppt has the same chance of being in each condition
What are repeated measures?
Same ppts take part in all conditions of the IV
What are strengths of the repeated measures?
Eliminates ppt variables
Fewer ppts so not as time consuming
What are limitations of repeated measures?
Order effects eg boredom may mean ppts don’t do as well in 2nd condition
How can we improve repeated measures?
Counterbalancing- half do condition 1 then 2 and the other 2 then 1
What are matched pairs?
Pairs of ppts are first matched on a variable that effects the DV then one member of each pair does each condition
What is a strength of matched pairs?
No order effects
Less demand characteristics
What is a limitation of matched pairs?
Time consuming and expensive to find matches
Large pool of ppts needed
Difficult to know which variables are appropriate for the ppts to be matched
