Week 5

Question 1

What is the goal of epidemiology

Answer 1

Identification of causes and preventions for disease

Question 2

What is strong evidence

Answer 2

1. Lowest possible random sampling error
2. Based on a strong design free of selection and information biases and under minimal influence of confounding

Question 3

What dose multivariate world mean

Answer 3

Never a simple exposure outcome model is never a reality relationships are multi variable

Question 4

What is confounding

Answer 4

Distortion of an actual association due to a mixing of effects between the exposure and an incidental variables

Question 5

Why dose confounding occur

Answer 5

Because the exposed group and the unexposed group are not exchangeable
They differ by factors other than their exposure status

Question 6

What is confounding a problem for

Answer 6

A problem for observational studies

Question 7

How can you reduce confounding

Answer 7

Randomization

Question 8

What is the criteria for defining a confounding variable

Answer 8

1. Casually associated with the outcome (true risk factor)
2. Noncausally or causally associated with the exposure
3. Not an intermediate in the causal pathway between exposure and outcome

Question 9

How do you deal with confounding at the design stage

Answer 9

Restriction (study only men or women)
Matching (case and control groups have similar characteristics
Randomization Experimental studies

Question 10

How do you deal with confounding at the analysis stage

Answer 10

Standardization (make 2 groups the same)
Stratfied anayalysis
Include confounding factors in a multivariate regression model

Question 11

What is effect modification

Answer 11

Where the exposure disease association changes over values of some third variable
Modifies the effects of the exposure on the outcome not a cause of the exposure and outcome
Don’t adjust just show how the effect modifier is operating

Question 12

Why is exploring effect modification important

Answer 12

Helps to understand the biology of an effect
We can identify high risk populations

Question 13

Difference between confounding and effect modification

Answer 13

The stratums RR are different then it is an effect modifier if they are the same its confounding

Question 14

What do you do if for confounding if your curde rr=adj rr

Answer 14

No major confounding use crude rr

Question 15

What do you do if Crude rr dosen’t = adj rr

Answer 15

Confounding is present use adj RR

Question 16

What is mediation

Answer 16

On the pathway an intermediary variable occurs between an exposure and an outcome do not need to adjust for the effects of the intermediaries in assessing exposure disease associations