Question

1.Loss to follow-up bias is an important concern in which type of epidemiologic study?

2.Which of the following is a method for controlling confounding in the analysis phase only of a study?

3.An analytic method that simultaneously adjusts for several variables (confounders) is called:

4.For a variable to be a confounder, it must be:

5.A study design method to control confounding involving the selection of study subjects so that potential confounders are distributed identically is called:

6.Residual confounding can result from:

7.When chance, bias, and confounding have been ruled out as alternative explanations for an association, we may conclude that the association is causal.

8.When the magnitude of the association between an exposure and disease is changed or modified by a third variable, this is known as

9.Effect modification is an arbitrary statistical phenomenon that should be controlled for and minimized in an analysis.

10.In effect modification, it is possible to have a relative risk associated with both factors that is larger than the product of the relative risk associated with each factor alone.

11.Effect modification is evaluated in stratified analyses through:

Answer 1

1)

Cohort and Experimental Studies

Experimental studies involve active manipulation of exposure (treatment/alternative treatment), whereas in cohort studies, the investigator must merely observe the effect of exposure. ... Random allocation (or randomization) is an essential part of a good experimental study.

2)

In observational studies, control of confounding can be done in the design and analysis phases. Using examples from large health care database studies, this article provides the clinicians with an overview of standard methods in the analysis phase, such as stratification, standardization, multivariable regression analysis and propensity score (PS) methods, together with the more advanced high-dimensional propensity score (HD-PS) method.

3)

Multivariate Analysis

4)

For a variable to be a

confounder, it must have three characteristics: 1) it must be associ-

ated with the exposure (causally or not); 2) it must be a cause, or a

surrogate of the cause, of the health outcome; 3) it should not be in

the causal pathway between the potential risk factor and outcome

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