RM: Experimental design Flashcards
What are experimental designs?
-how ppts are organized across the conditions
What is an independent groups design?
-each ppt is part of one condition only
-less demand characteristics and order effects
How are ppts randomly allocated?
-the lottery method (names out of a hat)
-random no. generator
What is a repeated measures design?
-each ppt takes part in both conditions
-all complete condition 1 and 2
What is a matched pairs design?
-each ppt takes part in 1 condition
-reduces ppt variables (similar in important qualities)
How is a matched pairs design done?
-matched on most important ppt variables
-fewer demand characteristics (experiment only completed once per ppt)
Strengths of independent group design?
-order effects reduced (no practice/order effects)
-reduced demand characteristics
Limitations of independent group design?
-ppts EVs may lower internal validity
-less economical (2x ppts needed)
How to fix problems with independent design?
-random allocation- reduces researcher bias/combats ppt variables
Strengths of repeated measures design?
-ppts EVs controlled for (same ppt repeats both conditions)
-less ppts needed (do both conditions)
Limitations of repeated measures design?
-order effects (practice/fatigue)
-demand characteristics
How to fix problems with repeated measures?
-counter-balancing (reversing order of conditions)
^ABBA
-reduces order effects
Strengths of matched pairs design?
-reduces order effects
-reduces demand characteristics
-ppt EVs are reduced (key variables matched)
Limitations of matched pairs design?
-ppts not truly matched (is still differences)
-more expensive/time-consuming
How to fix problems with matched pairs?
-no. of variables can be restricted (less to match ppts to), makes it easier to find matches
