Researchers Christelle Delmas and associates wanted to determine if having a television (TV) in the bedroom is associated with obesity. The researchers administered a questionnaire to 379 twelve-year-old French adolescents. After analyzing the results, the researchers determined that the body mass index of the adolescents who had a TV in their bedroom was signiﬁcantly higher than that of the adolescents who did not have a TV in their bedroom.
(a) Why is this an observational study? What type of observational study is this?
(b) What is the response variable in the study? What is the explanatory variable?
(c) Can you think of any lurking variables that may affect the results of the study?
(d) In the report, the researchers stated, “These results remain signiﬁcant after adjustment for socioeconomic status.” What does this mean?
(e) Can we conclude that a television in the bedroom causes a higher body mass index? Explain.