Experimental Research Designs

Question 1

What are the 3 basic experimental research designs?

Answer 1

Between-subjects (or independent measures) designs, within-subjects (or repeated measures) designs, and matched pairs designs.

Question 2

What is the key point of between-subjects research designs?

Answer 2

That different groups of participants are used.

Question 3

In between-subjects research designs, what does each group experience?

Answer 3

A different treatment/ condition (corresponding to the levels of the independent variable)

Question 4

In between-subjects research designs, what are all participants tested on?

Answer 4

The same outcome measure (the dependent variable)

Question 5

What would be the simplest between-subjects study design for the hypothesis that a new drug improves mood?

Answer 5

Testing the presence or absence of the independent variable (at 2 levels) by randomly assigning participants into 1 of the 2 conditions (which are both identical in every sense except for the presence/ absence of the IV).

Question 6

For a between-subjects study into whether a new drug improves mood, what could the conditions which each participant group are assigned to be?

Answer 6

1 condition could involve taking the new drug, and the other condition could involve taking a placebo.

Question 7

What are the merits of between-subjects research designs?

Answer 7

They are simple to implement and do not come with the risk of carry-over effects.

Question 8

What can sometimes happen with between-subjects research designs that can make them quite tricky to implement?

Answer 8

A participant can only be allocated to one condition (e.g. due to their gender/ a diagnosis).

Question 9

Which research design would be implemented in a between-subjects study if a participant can only be allocated to one condition?

Answer 9

A quasi-experimental design

Question 10

Why do between-subjects research designs make it harder for us to detect real differences?

Answer 10

Because they introduce variation.

Question 11

What must we take steps to control in relation to between-subjects research designs?

Answer 11

Any differences that we observe between groups that may be due to differences in participant characteristics.

Question 12

What is a matched pairs research design?

Answer 12

A between-subjects research design where groups of participants are matched by extraneous variables that might be relevant (e.g. IQ, age, or sex).

Question 13

What is the first step that needs to be taken when carrying out a matched pairs research design?

Answer 13

You need to assess your participants based on particular extraneous variables & find pairs that resemble each other.

Question 14

What needs to be done once you’ve assessed participants based on particular extraneous variables & found pairs that resemble each other in a matched pairs research design?

Answer 14

You then assign each member in every pair to each experimental condition.

Question 15

Are matched pairs research designs typically used in clinical or non-clinical conditions?

Answer 15

Clinical

Question 16

What do matched pairs research designs aim to reduce?

Answer 16

Variance between participants

Question 17

What are the disadvantages of matched pairs research designs?

Answer 17

They’re time-consuming & expensive, & you might not be aware of all of the relevant variables that need to be matched.

Question 18

What is the key point of within-subjects research designs?

Answer 18

That 1 group of participants are repeatedly tested.

Question 19

In within-subjects research designs, what does each group experience?

Answer 19

All treatments/ conditions (corresponding to levels of the independent variable)

Question 20

In within-subjects research designs, what are all participants tested on?

Answer 20

The same outcome measure (the dependent variable)

Question 21

What would be the simplest within-subjects study design for the hypothesis that a new drug improves mood?

Answer 21

Testing the presence or absence of the independent variable (at 2 levels) by randomly assigning participants to both conditions (which are both identical in every sense except for the presence/ absence of the IV).

Question 22

For a within-subjects study into whether a new drug improves mood, what could the conditions which each participant is assigned to be?

Answer 22

1 condition could involve taking the new drug, and the other condition could involve taking a placebo.

Question 23

What is the merit of within-subjects research designs?

Answer 23

There’s no risk of individual differences (which reduces variability)

Question 24

What are 2 issues with within-subjects research designs?

Answer 24

They could come with carry-over effects (i.e. a systematic effect being introduced), or the design may simply be impossible.

Question 25

What are 2 examples of carry-over effects that could occur as a result of a within-subjects research design?

Answer 25

Fatigue & practice/ learning effects.

Question 26

Why may a within-subjects research design be impossible?

Answer 26

If the treatment of interest is irreversible/ if the participant can only be allocated to 1 condition.