Question

One of your teachers tells your class that skipping class often can lead to dire consequences. He says that data from his previous classes show that students who often skip class have twice the risk of failing compared to students who attend regularly, even though class attendance and participation are not part of the grade. (a) What term from this chapter applies to the phrase "twice the risk?" baseline risk odds ratio relative risk (b) Give two reasons why the information provided by the teacher does not imply that if you skip class regularly you will probably fail the class. (Select all that apply.) The relative risk is based on an observational study, so it does not imply that skipping class causes people to get lower grades. The teacher did not provide a baseline risk. Perhaps the risk doubles from one student to two. The risk is calculated using categorical variables and suffers from an unmentioned third variable. Namely, "was the student likely to fail before skipping class." The statement about the risk is incomplete. The teacher did not specify anything about the age or grade of the participants. The teacher did not provide a relative risk for the study. Perhaps students who attend class are twice as likely to pass, rather than the other way around.

Answer 1

Ques 1: Relative risk because it is defined as "Relative risk is a ratio of the probability of an event occurring in the exposed group versus the probability of the event occurring in the non-exposed group"

Ques 2:

• The teacher did not provide a baseline risk. Perhaps the risk doubles from one student to two.
• The risk is calculated using categorical variables and suffers from an unmentioned third variable, namely, " was the student likely to fail before skipping class."