Research Methods Y1 - Control Of Variables

Question 1

What is an extraneous variable (EV)?

Answer 1

Any variable, other than the independent variable (IV), that may have an effect on the dependent variable (DV) if it is not controlled. EVs are essentially nuisance variables that do not vary systematically with the IV.

Question 2

What is a confounding variable?

Answer 2

Any variable, other than the IV, that may have affected the DV so we cannot be sure of the true source of changes to the DV. Confounding variables vary systematically with the IV.

Question 3

What are demand characteristics?

Answer 3

Any cue from the researcher or from the research situation that may be interpreted by participants as revealing the purpose of the investigation. This may lead to a participant changing their behaviour within the research situation.

Question 4

What are investigator effects?

Answer 4

Any effect of the investigator’s behaviour (conscious or unconscious) on the research outcome (the DV). This may include everything from the design of the study to the selection of, and interaction with, participants during the research process.

Question 5

What is randomisation in the control of variables?

Answer 5

The use of chance in order to control for the effects of bias when designing materials and deciding the order of conditions.

Question 6

What is standardisation in the control of variables?

Answer 6

Using exactly the same formalised procedures and instructions for all participants in a research study.

Question 7

Why might extraneous variables like age or IQ be described as ‘nuisance variables’?

Answer 7

These variables may muddy the experimental results if they are not controlled, potentially making it harder to detect a result.

Question 8

How can personality act as a confounding variable?

Answer 8

For example, if extraverts had been grouped with one condition, we would not know whether the difference in results was due to the IV or extraversion systematically affecting the DV.

Question 9

What are the steps researchers can take to reduce extraneous variables and confounding variables?

Answer 9

Randomisation: Using random chance to distribute participants evenly across conditions.

Standardisation: Ensuring all participants experience the same procedures and instructions to reduce variability.

Question 10

How can demand characteristics affect a participant’s behaviour?

Answer 10

Participants may act in a way that they think is expected (the ‘please-U’ effect), or they may deliberately do the opposite (the ‘screw-U’ effect), which could influence the dependent variable.

Question 11

What is the importance of using standardisation in an investigation?

Answer 11

Standardisation ensures that all participants are subject to the same environment, instructions, and experience so that variations in the DV can be attributed to the IV and not extraneous factors.