When a researcher asks the question, Have subjects been pre-selected so as to represent the extremes on the variable of interest? she is concerned with which one of the following potential threats to internal validity?
a. testing effect
b. maturation
c. subject selection
d. regression effect
Question 2
A change in behavior simply as a result of earlier experience in the study is a threat to _________validity.
a. internal
b. external
c. construct
d. statistical