Ratios

Question 1

What is a ratio?

Answer 1

A way to quantify the magnitude of association between 2 measutes

Question 2

Ways to calculate a ratio?

Answer 2

• odds ratio

- relative risk

Question 3

What do ratios measure?

Answer 3

Exposure and disease

• Ex: smoking cigarettes and developing lung cancer.
• Ex: aerobic exercise and obesity

Question 4

What do OR/RR do?

Answer 4

Measure association between a binary outcome variable and binary predictor variable
-both are complete different

Question 5

Whats RR best used for?

Answer 5

Incidence data

-cohort design

Question 6

Whats OR best used for?

Answer 6

No incidence data

• case control
• cross sectional

Question 7

Numerator/denominator in RR?

Answer 7

• num. is risk is diseaese of exposed

- denom. is risk of disease of non exposed

Question 8

RR formula?

Answer 8

a/a+b / c/c+d

Question 9

Ratios>1 indicate?

Answer 9

Rate is higher among exposed than unexposed

Question 10

Ratios=0 indicate?

Answer 10

Equal assiciation

Question 11

Ratios<1 indicate?

Answer 11

Indicate the rate is lower among exposed than unexposed

Question 12

Num/denom in OR?

Answer 12

Odds of disease in exposed/. odds of disease in unexposed

Question 13

OR formula?

Answer 13

ad/bc

Question 14

A decrease in standard error means?

Answer 14

Confidence interval is smaller

Question 15

95% CI

Answer 15

Find the OR/RR and then find the 95% CI around that

-null hypothesis: OR/RR=1