Controls, demand characteristics and investigator effects

Question 1

What is an extraneous variable?

Answer 1

Any other variable other than the IV that might affect the DV and thus the results.

Question 2

What measures can we use to control extraneous variables?

Answer 2

Random allocations
Counterbalancing
Randomization
Standardization

Question 3

Explain the two types of extraneous variables.

Answer 3

Participant variables - When characteristics such as age or gender among the participants can influence their behavior and any prior knowledge to the task.

Situational variables - Environmental factors that could influence behavior e.g. noise or temperature.

Question 4

What are order effects?

Answer 4

In repeated measure designs, the participant has already completed one condition which can alter the behavior in the second condition for example performance decreases due to fatigue or increases due to practice.

Question 5

Explain random allocations and what variable they control.

Answer 5

Randomly allocating participants to different groups. This is used to control participant variables. Participant variables such as age or gender are more likely to be spread out if randomly allocated.

Question 6

Explain counterbalancing and what variable they control.

Answer 6

Counterbalancing splits the sample of participants in half with one half completing the two conditions in one order and the other half completing the conditions in the reverse order. Any effect due to practice or fatigue is cancelled out and any order effects should be controlled but not completely eliminated.

Question 7

Explain standardisation and what variable they control.

Answer 7

This is the process where all situational variables of a procedure used in research are kept identical so that each participant has the same experience

Question 8

Explain randomisation and what variable they control.