Research Methods: Experimental Design Flashcards
What is an independent groups designs
There are different ppts in each group
E.g. one group doing a task with an audience and the other one doing it alone
This avoids the problem that ppts doing the test in both conditions, they may improve in performance due to them two goes at the task (confounding variables)
Advantages of independent groups designs
No order effects: no one gets better through practice or gets worse through being bored or tired
Disadvantages of independent groups designs
Participant variables: differences between the people in each group might affect the results (e.g. people may just be better at the task)
What is a repeated measures design
Where all participants undergo both conditions of the experiment
You can compare the performances in each condition knowing the differences weren’t due to ppt variables
Advantages of repeated measures design
Participant variables: now the same people do the test in both conditions, so any differences between individuals shouldn’t affect the results
Number of participants: fewer participants are needed to get the same amount of data
Disadvantages of repeated measures design
Order effects: if all participants did a specific condition first, any improvements in the second condition could be due to practice, not the audience’s absence
What is a matched pairs design
There are different participants in each condition, but they’re matched on important variables (like age, sex and personality)
E.g. the if ppts are paired on a relevant characteristic such as age, then the two members of the pair are randomly assigned to either condition ensure that each condition has a similar age range
Advantages of matched pairs design
No order effects: there are different people in each condition
Participant variables: important differences are minimised through matching
Disadvantages of matched pairs design
Number of participants: need twice as many people compared to repeated measures
Practicalities: time-consuming and difficult to find ppts who match
Why does research need to be highly controlled
It avoids the effects of the extraneous variables
How can extraneous variables be controlled
They are controlled in a study so they’re kept constant for all ppts
E.g. everyone does the task in the same place so distractions are distractions are similar
How can extraneous variables be eliminated
Everyone could do the task somewhere with no noise distractions
What are the ways research can be controlled to eliminate extraneous
Counterbalancing
Random allocation
Standardised instructions
Randomisation
What is counterbalancing
Half the ppts do the task with a condition and then in the other
Others do the conditions the other way round
Any order effects would then be equal across conditions
What is random allocation
Can be done by drawing names out of a hat
Means everyone has an equal chance of doing either condition
Ensures groups are not biased on key variables e.g. sex (one group could have more men than the other)
