Experimental Designs

Question 1

Repeated measures

Answer 1

The same participants take part in each condition of the IV.

This means that each condition of the experiment includes the same group of participants.

Question 2

Repeated measures:
Control of participants
😄

Answer 2

As this time participants are used in each condition, participant variables are reduced.

Question 3

Repeated measures:
Order effects
😔

Answer 3

The order of conditions may have an effect on the participants behaviour e.g. practice effects of fatigue effects, this can be controlled by counterbalancing ➡️ The sample is split into two groups 🅰 and 🅱 e.g. group one does ‘A’ then ‘B’, then group two does ‘B’ then ‘A’ – this eliminates order effects. Order effects still occur for each participant but they occur equally in each group, so they balance each other out in the results.

Question 4

Repeated measures:
Demand characteristics
😔

Answer 4

If the participants experience both conditions they may realise the difference between them i.e. guess the aim.

Question 5

Repeated measures:
Time
😔

Answer 5

Takes twice as long as independent groups as they test two conditions using the same participants.
Participants may need to rest between the conditions.

Question 6

Repeated measures:
Number of participants needed / Amount of data collected
😄😔

Answer 6

Fewer participants are needed as they take part in both conditions.
Two sets of results from each condition.

Question 7

Matched pairs

Answer 7

Each condition uses different participants that are matched in terms of important characteristics which are relevant to the study e.g. sex age intelligence.
R.A.P - each pair is separated into one condition.

Question 8

Matched pairs:
Control of PVs
😄😔

Answer 8

Based together on similarities, so some PVs are reduced.
BUT…
You can only match on variables relevant to the study, but it could be other participant variables affecting their behaviour ➡️ conduct a pilot study (initial run through of procedures to be used in an investigation)

Question 9

Matched pairs:
Order effects
😄

Answer 9

Avoided as participants only take part in one condition.

Question 10

Matched pairs:
Demand characteristics
😄

Answer 10

Participants may not be aware of being paired so won’t act any different. Participants only experience one condition.

Question 11

Matched pairs:
Time
😔

Answer 11

Takes the researcher a lot of time to match participants closely in pairs ➡️ could restrict matching variables but pairs won’t be as similar.

Question 12

Matched pairs:
Number of Ps/amount of data
😔

Answer 12

If one participant drops out you’ve lost two participants data.
Likely to have a large number of participants to ensure you can obtain matched pairs on key variables.

Question 13

Independent groups:

Answer 13

Different Ps are used in each condition of the IV.

Question 14

Independent groups:
Control of PVs
😔

Answer 14

Poor control because they are different Ps in each condition, PVs may affect behaviour not the IV. ThIs can be solved theoretically by R.A.P (distributes variables equally).

Question 15

Independent groups:
Order effects
😄

Answer 15

Avoided as Ps only take part in one condition.

Question 16

Independent groups:
Demand characteristics
😄

Answer 16

Unlikely as Ps only experience one condition.

Question 17

Independent measures:
Time
😄😔

Answer 17

Takes less time to conduct study as both conditions can occur at the same time.
More Ps are needed so study may be more time consuming.

Question 18

Independent groups:
Number of Ps/ amount of data
😔

Answer 18

Twice as many Ps than repeated measures.