Let us pretend that the U.S.Department of Agriculture does regular surveys on mature Americans to see what concerns they have with foodborne illnesses.You hear on the news one night that mature Americans are now 50 times more likely to worry about Mad Cow disease than they were five years ago.You happen to remember that there was an outbreak of Mad Cow disease last year at around the same time the data were collected).It is possible that the increase in concern over Mad Cow disease is partially due to the recent outbreak.This is an example of __________ being a threat to internal validity.
A)history
B)maturation
C)regression to the mean
D)selection

Question

Quizplus · Accepted Answer

History refers to external events that may occur during the study that could affect the outcome. The outbreak of Mad Cow disease is an external event and may have influenced the responses of mature Americans in the survey, making it a threat to internal validity.

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