Confounding

Question 1

Magnitude of confounding equation

Answer 1

= (RR crude - RR adjusted) / RR adjusted

Question 2

Positive confounding

Answer 2

True RR is 1.0, confounded RR is 2.0

Question 3

Negative confounding

Answer 3

True RR is 3.0, confounded RR is 2.0

Question 4

confounding by indication

Answer 4

treatments are given to individuals with a particular disease, therefore a mixing of effects between the treatment, the disease for which the treatment is given, and the outcome under study

Question 5

confounding by severity

Answer 5

the severity of the disease is the potential confounder

makes the therapy appear less effective in obs studies compared to exp studies

Question 6

3 main ways to control confounding in the design stage

Answer 6

randomization, restriction(limiting who may participate in the study) BUT makes difficult to find subjects and limits generalizability, matching (making study and comparison groups similar w/respect to extraneous factors) BUT is expensive, can overmatch

Question 7

3 main ways to control confounders in analysis stage

Answer 7

standardization, stratification, and multivariate methods

Question 8

Residual confounding

Answer 8

confounding that remains even after many confounding variables have been controlled

may arise from uncollected data, persistent differences in risk within a category of a confounder, and when the confounder is misclassified

Question 9

Effect measure modification

Answer 9

change in the strength of an association between an exposure and disease according to the level of a 3rd variable

Question 10

3 criteria that need to be fulfilled to be a potential confounder

Answer 10

variable needs to be associated with the exposure
variable needs to be associated with the outcome/disease
variable is not an intermediate in causal pathway between exposure and outcome

Question 11

What is the purpose of controlling for confounding?

Answer 11

to get a more precise estimate of the true association between the exposure and the disease/outcome

Question 12

what 3 aspects of a study must be evaluated before declaring a statistical association?

Answer 12

confounding/effect modification, bias, stratified significance

Question 13

confounding definition

Answer 13

the mixing of effects between an exposure, an outcome, and a 3rd extraneous variable