Experimental Design

Question 1

What is an independent group design?

Answer 1

1. Means there are different participants in each group,
2. In example, one group does the task with an audience and the other group does it without,
3. This avoids the problem of participants performance being improved by repetition of the task.

Question 2

Advantages of Independent group design?

Answer 2

1. No order effects - no one gets better through practice or get worse through boredom or tiredness.

Question 3

Limitations of independent group design?

Answer 3

1. Participant variables - differences between individuals in each group might affect the results,
2. Number of participants - twice as many participants are needed to get the same amount of data.

Question 4

What is a repeated measures design?

Answer 4

1. Using the prior example, all participants would do the task with an audience and then without,
2. Can compare the performances in each condition knowing the differences weren’t due to participant variables.

Question 5

Advantages of repeated measures design?

Answer 5

1. Participant variables - now the same people do the test in all conditions, so any differences between individuals shouldn’t affect the results,
2. Number of participants - fewer participants are needed to get the same amount of data.

Question 6

Limitations of repeated measures design?

Answer 6

1. Order effects - if all participants did one condition first, any improvements in the second condition could be due to practice rather than the tested variable.

Question 7

What is a matched pairs design?

Answer 7

1. Means that there are different participants in each condition, but they are matched on important variables (e.g. age, sex, and personality),
2. Participants are paired on a relevant characteristic, such as age, and then the two members of the pair are randomly assigned to either the ‘audience’ or ‘no audience’ condition to ensure that each condition has a similar age range.

Question 8

Advantages of matched pairs design?

Answer 8

1. No order effects - there are different people in each condition,
2. Participant variables - important differences are minimised through matching.

Question 9

Disadvantages of matched pairs design?

Answer 9

1. Number of participants - need twice as many people compared to repeated measures,
2. Practicalities - time-consuming and difficult to find participants who match.

Question 10

How can extraneous variables be controlled?

Answer 10

1. Counterbalancing,
2. Random allocation,
3. Standardised instruction,
4. Randomisation.

Question 11

What is counterbalancing?

Answer 11

1. Mixing up the order of the tasks,
2. In example, half the participants do the task with an audience first and then without. The others do the conditions the other way round. Any order effects would then be equal across conditions.

Question 12

What is random allocation?

Answer 12

1. Assigning people to groups through a randomised process (e.g. drawing names out of a hat),
2. In example, an independent measures study with, for example, more men in one group than the other could have a confounding variable. Any difference in performance may be due to sex rather than the real IV,
3. Random allocation should ensure groups are not biased on key variables.

Question 13

What is standardised instruction?

Answer 13

1. Ensures that experimenters act in a similar way with all participants,
2. Everything should be as similar as possible for all the participants, including each participant’s experience in such studies.

Question 14

What is randomisation?

Answer 14

1. When the material is presented to participants in a random order,
2. It avoids the possibility of order effects,
3. In example, in a repeated measurs memory experiment, participants may be asked to learn a list of words in two different conditions. In each condition, the words on their list would be in a random order.

Question 15

What is a pilot study?

Answer 15

1. Should establish whether the design works, whether participants understand the wording in instructions, or whether something important has been missed out,
2. Also give researchers practice at following the procedures. Problems can be tackled before running the main study, which could save wasting time and money,
3. Pilot studies allow the validity and reliability of the test to be assessed in advance, which then gives the opportunity for improvements to be made.