Experimental design Flashcards
1
Q
Repeated measures
A
- all participants receive levels of the IV
e.g each participant does the task with the TV on and then a week later each participant does a similar test without TV on
2
Q
Disadvantages of repeated measures
A
- the order of conditions may affect performance
e.g participants may do better on the second because of a practice effect or because they are less anxious- to fix this researchers may use two different tests to reduce a practice effect though the two tests must be equivalent
- when participants do the second test they may guess the purpose of the experiment, which may affect their behaviour
e.g some participants may purposely do worse on the second test because they want to appear as if they work less well in the afternoon - to fix this a cover story can be presented
3
Q
Advantages of repeated measures
A
- do not need that many participants because the same participants are completing the experiment each time
- do not need to control participant variables
- allows us to see a clear difference n the research due to the fact that it is the same group of people
4
Q
Independent groups
A
- participants are placed in seperate independent groups and each group does one level of the IV
e.g group A does the task with the TV on - one level of the IV
group B does the task with no TV - the other level of the IV
5
Q
Disadvantages of independent groups
A
- the researcher cannot control the effects of participant variables e.g the different abilities of each participant
e.g in Group A the participants may happen to have better memories - would be a confounding - randomly allocate participants to conditions which distribute participant variable - can be done by by putting participants names in a hat and drawing out the names
- independent groups design needs more participants than repeated measures design in order to end up with the same amount of data
6
Q
Advantages of independent groups
A
- this design avoids the effects of participants doing better on one condition than the other - because participants only does one condition
-more difficult for them to guess the aim of the experiment as they are only doing one condition
7
Q
Matched pairs
A
- A compromise is to use the two groups of the participants but match participants on key characteristics believed to affect performance
- one member of the pair is matched to group A and the other Group B - the procedure is then the same as the independent groups
- the characteristics must be relevant to the study
8
Q
Disadvantages of matched pairs
A
- very time consuming and difficult to match participants on key variables, the researcher probably has to start with a large group of participants to ensure they can obtain matched pairs
- to fix this, restrict the number of variables to make it easier
- conduct a pilot study to consider key variables that might be important
- it is not possible to control all participants variables because you can only match on variables known to be relevant but it could be that others are important
e.g in a memory experiment you might match on memory abilities but later find that some of the participants had been involved in a teaching programme to boost memory skills
9
Q
Advantages of matched pairs
A
- this design avoids the effects of participants doing better on one condition than the other - because participants only does one condition
- no chance of guessing the experiment
10
Q
What is counterbalancing?
A
- an experimental technique used to overcome order effects when using when using repeated measures design
- ensures that each condition is tested first or second in equal
11
Q
How do you counterbalance?
A
two ways to counterbalance and there are two conditions
- condition A - test done in morning
- condition B - test done in afternoon
- AB or BA
divide participants
group 1 - each participant does A then B
group 2 - each participant does B then A - ABBA
all participants take part in each condition twice
Trial 1 - Condition A
Trial 2 - Condition B
Trial 3 - Condition B
Trial 4 - Condition A
