Rye County Hospital’s Wellness Center is testing two programs to get smokers to quit. STOP is offered on Tuesday nights, and QUIT is offered on Thursday nights. Ninety smokers volunteered to be subjects. They will be randomly assigned to STOP, QUIT, or No Treatment (neither group).

a. What two threats to internal validity are controlled by random assignment?

b. About the time the smoking study started, cigarette taxes increased sharply. Would this affect the internal validity of the study? Justify your answer.

c. Several subjects assigned to QUIT had a schedule conflict with their aerobics class. Before the program began, a secretary let them trade places with subjects assigned to STOP. Comment on how the secretary’s action probably affected the study’s internal validity.

Answer rating: 100% (QA)

a Random assignment helps control for two important threats to internal validity Selection Bias Random assignment ensures that each smoker has an equa... View the full answer