Experimental design

Question 1

What is an experimental design?

Answer 1

Refers to how participants are allocated to the different conditions in an experiment

Question 2

What are the 3 types of experimental design?

Answer 2

1. Independent groups
2. Repeated measures
3. Matched pairs design

Question 3

What is an independent groups design?

Answer 3

Different participants are used in each condition of the independent variable

Question 4

What is a repeated measures design?

Answer 4

The same participants take part in each condition of the independent variable

Question 5

What is a matched pairs design?

Answer 5

Participants are paired on a variable and then one of each pair is allocated to each experimental condition

Question 6

What are order effects?

Answer 6

An extraneous variable arising in a repeated measures design from the order in which conditions are presented. E.g. practice effect or fatigue effect

Question 7

What is counterbalancing?

Answer 7

An experimental technique used to overcome order effects in a repeated measures design: half the participants experience the conditions in one order and the other half in the opposite order.

Question 8

What is random allocation?

Answer 8

Allocating participants to experimental groups or conditions using random techniques.

Question 9

What is the advantage of a repeated measures?

Answer 9

Participant variables are controlled for

Question 10

What is the disadvantage of repeated measures?

Answer 10

Order effects- repeating 2 tasks could create boredom or fatigue leading to deterioration in performance on 2nd task. Or could lead to practice effects where participants’ performance improves

Question 11

How can we overcome order effects in a repeated measures study?

Answer 11

Counterbalancing

Question 12

What are the two advantages Independent groups?

Answer 12

-No order effects
-Participants less likely to guess the aim of the experiment

Question 13

What are the two disadvantages of independent groups Independent groups?

Answer 13

-Participant variables are not controlled for
- Less economical- need more participants

Question 14

How can you control participant variables in an Independent groups study?

Answer 14

Random allocation

Question 15

What are the two advantages of Matched pairs design?

Answer 15

• Less likely to have demand characteristics and order effects
• Reduces influence of participant variables

Question 16

What are the two disadvantages of Matched pairs design?

Answer 16

• Less economical= Time-consuming
• Not possible to control all participant variables as can only match on variables known to be relevant, but could be others are important.

Question 17

How can you make it more economical and control ptpt variables in a Matched pairs study?

Answer 17

• Restrict the number of variables to match on to make it easier
• Conduct a pilot study to consider key variables that might be important when matching.