If the manipulation of an independent variable inadvertently manipulates a second variable that is actually responsible for observed effects on a dependent variable, which of the following statements is true?
A)The second variable should be included as a factor in the experimental design.
B)The second variable is a threat to the study's internal validity.
C)This is an example of extraneous manipulation.
D)This is an example of confounding.
E)Both (b)and (d).

Question

Quizplus · Accepted Answer

Inadvertently manipulating a second variable that is actually responsible for observed effects on a dependent variable is an example of confounding, which threatens the study's internal validity. Therefore, both choices (b) and (d) are correct. It is important to include the second variable as a factor in the experimental design to control for its effects and to ensure that the observed effects on the dependent variable are due to the intended manipulation of the independent variable.

If the Manipulation of an Independent Variable Inadvertently Manipulates a Second