Experimental Design Flashcards
(12 cards)
Independent groups
Each participant only takes part in only one condition
They are allocated randomly to either the experimental or control group
Repeated measures
Each participant takes part in both (experimental and control) conditions and their performance in each is compared
Matched pairs
Different participants are used in each condition, but they are matched as closely as possible on key variables like age, IQ, or personality
The characteristic for matching is usually relevant to the experiment
Each pair randomly contributes one member to the control and experimental group so the 2 groups are as evenly matched as possible
Strengths of Independent Groups
Less materials needed because test can be used for both groups as only doing one condition
No order effects e.g. bored, tired as different participants in each condition
Less chance of demand characteristics as participants are less likely to guess the aim of the study
Limitations of Independent Groups
More participants needed as different participants in each condition, so need a larger sample
Individual differences, different participants in each condition so comparing results of each condition is not as accurate
One type of person ends up in each condition
Ways to overcome limitations of Independent Groups
Random allocation:
• Names of all participants in a hat
• Draw them out one by one
• Allocate alternately to condition 1/2
Strengths of Repeated Measures
Less participants needed
No individual differences
Limitations of Repeated Measures
Order effects (e.g. bored, tired, practice) may mean participants do better the 2nd time due to practice, or worse due to boredom
More chance of demand characteristics
More materials needed
Ways to overcome limitations of Repeated Measures
Counterbalance order effects:
Group 1 -> Condition A -> Condition B
Group 2 -> Condition B -> Condition A
Strengths of Matched Pairs
Less chance of individual differences as participants are matched to reduce the impact of individual differences
No order effects as there are different participants in each condition
Less chance of demand characteristics as participants are less likely to guess the aim of the study as they only do one condition
Limitations of Matched Pairs
More participants needed
More materials needed
Time consuming
Matching is difficult
Ways to overcome limitations of Matched Pairs
Larger sample size
> Mitigates impact of individual differences
Careful consideration of matching criteria
> Appropriate matching variables based on the specific research question and the potential confounding variables
