Should You Believe This Study?

Question

Suppose a sociologist studying obesity in America passes out questionnaires asking each respondent if he or she exercises regularly. Based solely on this information, would you have reason to question the study? Mark all that apply. (There could be more than one correct response.)
 
 
 

a)Yes, because the study should have been double blind.
 

b)Yes, because passing out questionnaires can lead to participation bias.
 

c)Yes, because self-reporting is not always accurate.
 

d)Should You Believe This Study?No, there is no reason to question the study.

Answer 1

b) and c) are clearly true.  Since they are true d) is false.  a) is also false since double blind terminology only refers to experiments and this is an observational study, not an experiment.