Experimental design Flashcards
What is an independent groups.
Is when 2 separate groups of participants experience 2 different conditions of the experiment.
Two levels of independent variables (IV) means that all participants experience one level of IV only.
What are the strengths of independent groups?
Participants are less likely to guess the aim of the study, and there are no order effects- effects arising from having completed two tasks, for example becoming more practised and doing better in the second condition, or getting bored/fatigued and doing worse in the second condition
What are the limitations of independent groups?
There may be differences between the two groups of people- e.g. intelligence, age, gender (participant variables). These differences may act as a confounding variable, reducing the validity of the findings.
Less economical - Twice as many participants are needed.
How is participant variables in independent groups addressed?
Random allocation.
What are repeated measures?
Is when all participants experience both conditions of the experiment.
What are strengths of repeated measures?
Participant variables are controlled therefore higher validity.
Fewer participants are needed therefore less time spent recruiting them.
What are the limitations of repeated measures?
There are order effects which may influence the results.
Repeating two tasks could create boredom or fatigue that might cause deterioration in performance.
Participant can also improve since participants would perform better the second try.
Participants may work out the aim of the study (demand characteristics).
How is order effects in repeated measures addressed?
Counterbalancing- half the participants do one task followed by the second (A followed by B) and the other does the opposite (B followed by A).
What is are matched pairs?
As independent groups, but participants are ‘matched’ on qualities relevant to the experiment.
Participant from each pair are allocated to a different condition of the experiment.
What are the strengths of matched pairs?
Participants only take part in a single condition so order effects and demand characteristics are less of a problem.
Participant variables are reduced.
What are the limitations of matched pairs?
Participants can never be matched perfectly, so there might still be some participant variables.
Matched pairs is the most time-consuming and expensive design to use.
Why is the independent group appropriate for memory experiment?
As the participants need to be different ages in each condition.
