Question

1) Investigators found a RR = 1.90 to explain the association between maternal education (high vs. low) and onset of adolescent eating disorders. They should therefore conclude that adolescents whose mothers had high education had a 90% greater risk of developing eating disorders than adolescents whose mothers had low education.

A. True

B. False

2) When examining an association between an exposure and an outcome, researchers may find a small effect that is statistically significant but could lack practical importance or "clinical significance."

A. True

B. False

3) Effect modification occurs when the effect of the exposure on the outcome is modified by a third variable. A. True B. False 59. Investigators are exploring the relationship between number of hours worked per week and cardiovascular disease among academic faculty in the United States. During their analysis, they find that the number of hours worked per week and cardiovascular disease are both associated with sedentary behavior (number of hours sitting). Is sedentary behavior more likely to be a confounder or a mediator of this association between number of hours worked and cardiovascular disease?

A. Confounder

B. Mediator

4)

Investigators explored the relationship between coffee drinking and osteoporosis using a case-control study. They calculated the overall odds ratio and odds ratios among smokers and non-smokers. The results are shown below.

OR (overall) = 2.20

OR (smokers) = 5.0   

OR (non-smokers) = 1.0

In this example, would smoking be best considered an effect modifier, mediator, or confounder for the relationship between coffee consumption and osteoporosis?

A. Confounder

B. Mediator

C. Effect modifier

Answer 1

1. False, the RR is the ratio of the probability to an event ocurring in the exposed group compared to the probability of the same event ocurring in an not exposed group, it is not a probability, so it shouldn´t be interpretate as that. Specifically, when the number is higher than 1, it means the event it´s more likely to ocurred in the exposed group compared to the non exposed group.

2. It is true, a statisticall significance doesn´t have to mean a practical importance, it just means that a variable has an effect on another variable. The significance is giving by us depending on the situation, depending if it important to the health of a person.

3) True. A effect modification ocurrs when a third variable modifies the effect of a risk factor on a situation (usually a disease).

59. A. Mediator. Sedentary behavior is more likely to be a mediator, because probably has the influence of the independent variable (the number of hours worked per week) to the dependent variable (cardiovascular disease), and not just gives an effect on the association of the number of hours worked per week and cardiovascular disease.

4. It is a effect modifier, cause is a third variable (smoking) that modifies the magnitude of the effect of a risk factor (coffe consumption) on the disease (osteoporosis). It is not a mediator because there is no casual relationship between these variables. Also, it is not a confunder because is not a distortion for mixing another factors associated with the outcome.