Experimental designs

Question 1

What is meant by experimental designs?

Answer 1

The different ways in which the testing of participants can be organised in relation to the experimental conditions.

Question 2

Which type of experiment involves participants experiencing only one of the experimental conditions?

Answer 2

Independent groups.

Question 3

What is an independent groups design?

Answer 3

Participants are allocated to different groups where each group represents one experimental condition.

Question 4

In a repeated measures design, how many different levels of the IV does each participant experience?

Answer 4

Each participant experiences every level of the IV.

Question 5

How is data from an independent group design analysed?

Answer 5

The performance of the two conditions is compared, we would normally compare the means of each group and look at the range of values.

Question 6

What is a matched pairs design?

Answer 6

Where pairs of participants are matched on some variables that may affect the DV. Then one member of the pair is assigned to condition A and one member is assigned to condition B.

Question 7

In which experimental design is it most likely that participants will figure out the aims of the study?

Answer 7

Repeated measures because they experience all of the conditions and there is an increased likelihood they will become wise to the aims of the study.

Question 8

What is a repeated measures design?

Answer 8

Where all participants take part in all conditions of the experiment.

Question 9

Why might results from a repeated measures design be better than results from an independent groups design.

Answer 9

Because it ensures they are compared ‘like-for-like’ as it is the same person in both conditions, whilst independent groups assesses the performance of two different people, where participant variables can com into play.

Question 10

What is random allocation?

Answer 10

An attempt to control for participant variables in an independent groups design which ensures that each participant has the same chance of being in one condition to another.

Question 11

In an independent groups design, how many different levels of the IV does each participant experience?

Answer 11

Only 1.

Question 12

What is counterbalancing?

Answer 12

An attempt to control for order effects in a repeated measures design: half the participants experience the conditions in one order and half in the other order.

Question 13

In an independent groups design with 2 levels of the IV, how many different participant groups would there be and what would they be called?

Answer 13

There would be 2 groups; one is the experimental group and one is the control group.

Question 14

In which experimental design is counterbalancing used?

Answer 14

In a repeated measures design.

Question 15

What type of experiment involves participants experiencing all conditions of the experiment?

Answer 15

Repeated measures.

Question 16

In a repeated measures design with 2 levels of the IV, how many different participant groups would there be and what would they be called?

Answer 16

There would be two groups, condition A and condition B. They would both experience all levels of the IV, however, the group they are in determines in what order they will experience the conditions.

Question 17

Which Swedish pop group took their name from a way of reducing order effects in a repeated measures design?

Answer 17

ABBA.

Question 18

The matched pairs design attempts to control which type of variable?

Answer 18

The confounding variable of participant differences.

Question 19

In an independent groups design, how are participant differences overcome?

Answer 19

To deal with the problem the researchers use random allocation.

Question 20

What type of variable is participant variables?

Answer 20

Participant variables are confounding variables.

Question 21

Why is random allocation used?

Answer 21

It is used in independent groups designs to reduce the effects of participant variables.

Question 22

In a study to test memory, suggest what participants may be paired up by in a matched pairs design.

Answer 22

Something that may affect their cognitive ability - IQ etc.

Question 23

What are the negatives of independent groups design?

Answer 23

• Participant variables affect the DV.

- Not very economical.

Question 24

Explain why independent groups designs are not very economical?

Answer 24

Because each participant only submits one answer, twice as many participants would be needed to produce equivalent data in a repeated measures design.

Question 25

How are participants paired up in a matched pairs design?

Answer 25

They are paired based upon a single variable or a combination of variables that are relevant to the experiment.

Question 26

What are the positives of using an independent groups design?

Answer 26

The main strength is that order effects are not a problem, the participants are also less likely to discover the aims of the experiment.

Question 27

What is the biggest issue for the repeated measures design?

Answer 27

The biggest issue is that each participant has to do at least two tasks and the order of these tasks may be significant in the results (caffeine may still be present in the body during the control).

Question 28

What is the biggest issue with an independent groups design?

Answer 28

The participants who occupy the different groups are not the same, a mean difference found between the two groups may be due to individual participant differences rather than the effects of the IV.

Question 29

How do researchers attempt to mitigate the influence of order effects?

Answer 29

Counterbalancing, also known as ABBA.

Question 30

In a matched pairs design, what happens after the pairs are allocated?

Answer 30

The experiment continues as if it were an independent groups design.

Question 31

What are order effects?

Answer 31

They are effects that come into play when repeating a task that could cause deterioration or improve the participants performance.

Question 32

Do order effects make the participant perform better or worse?

Answer 32

Trick question - it depends on the activity they are doing.

Question 33

What are the strengths of a repeated measures design?

Answer 33

• Controlled participant variables,

- Fewer participants needed as economically efficient.

Question 34

Which type of variables are order effects?

Answer 34

Order effects are confounding variables.

Question 35

Explain why demand characteristics are a problem for repeated measures designs.

Answer 35

It is more likely that a participant will figure out the aims of a study as they experience all conditions of the experiment. Therefore, demand characteristics tend to come into effect.

Question 36

Explain the process of counterbalancing:

Answer 36

Half the the participants take part in condition A then B, and the other half take part in condition B then A.

Question 37

It is established that independent groups is less economical than repeated measures because it requires double the participants for the same amount of data, comment on this for matched pairs.

Answer 37

Matched pairs is the least economical because matching requires lots of time and money, particularly if a pre-test is required.

Question 38

What are the negatives for a matched pairs design?

Answer 38

Although there is effort to reduce participant variables, they can never be completely matched and even when MZ twins are used there are still important differences between them. It is also the least economical design.

Question 39

What are the different types of experimental design?

Answer 39

• Independent groups,
• Repeated measures,
• Matched pairs.

Question 40

What are the positives for a matched pairs design?

Answer 40

Participants only take part in a single condition so order effects and demand characteristics are less of a problem, the effects of participant variables can be significantly reduced compared to an independent groups design.