09_ Confounding Variables

Question 1

what are Extraneous variables?

Answer 1

are any variables that influence the outcome of a study, but they are not the variables that are of interest.

Example: I randomly assign 50 students to two groups and administer the research methods final exam in the first week of class. What can I expect from the results?

• Prior knowledge is an extraneous variable. It will impact how well students perform on the exam.

Question 2

Because of random assignment to groups, the error resulting from the ___

Answer 2

extraneous variable will be distributed evenly across both groups.

Question 3

Confound: A variable that is related to ____

Answer 3

the IV and influences the DV; a factor other than the IV that can cause a result

Question 4

Random Assignment (Extraneous variables?)

Answer 4

• Does not reduce the amount of error that comes from extraneous variables (non-confounding), it only equalizes the error across groups.

• Error variance or random error or “noise”

• Does reduce the amount of error that comes from confounding variables.
• Systematic error

Question 5

NOT all extraneous variables become ___

Answer 5

confounding variables!

• What does the prior research identify as confounds?
• -Does it seem logical given the context that the variable would be a confound?

Question 6

Final Thoughts

To confound = to confuse

Answer 6

• Confounds provide alternative
interpretations of hypotheses
• Can affect variability between or within
groups
A critical aspect of research is controlling for confounds.

Question 7

Non-random assignment is a common ___

Answer 7

source of confounding