Odds Ratio

Question 1

T or F: If the probability of a success > p, then the odds in favor of success = p/(1 −p). If two proportions p1, p2 are considered and the odds in favor of success are computed for each proportion, then the ratio of odds, or OR, becomes a useful measure for relating the two proportions.

Answer 1

False, success = p

Question 2

When incidence rates are _________, comparing rates using a ratio measure of association is best done with a _____________. However, when incidence data are __________, the most commonly used method for comparing rates as a ratio is the _____________.

Answer 2

available, relative risk, not available, odds ratio (OR)

Question 3

odds ratio can be used to ________________ in any study design. This makes the odds ratio a very widely used _________________.

Answer 3

measure associations, measure of association

Question 4

__________ is a measure association that provides the strength and direction of the association between exposure and outcome in a population.

Answer 4

odds ratio

Question 5

T or F: the results of the odds ratio are interpreted in the same
manner as the relative risk.

Answer 5

True

Question 6

An odds ratio equal to 1 indicates that there is ___________between exposure and outcome in the observed populations.

Answer 6

no relationship

Question 7

An odds ratio greater than 1 indicates a
_____________ between exposure and outcome

Answer 7

positive association

Question 8

an odds ratio less than 1 indicates a
__________________ between exposure and outcome

Answer 8

negative association

Question 9

Exposure Odds Ratio Formula

Answer 9

𝑎/𝑐 / 𝑏/d

Question 10

exposure odds in those with outcome is represented by ___ because it is the number of people in the outcome group with exposure divided by the number of people in the outcome without exposure.

Answer 10

a/c

Question 11

the exposure odds in those without outcome are represented by b/d because it is the number of people without outcome with the exposure divided by the number of people without exposure.

Answer 11

b/d

Question 12

traditional odd ratio formula

Answer 12

𝑎𝑑 / 𝑏c

Question 13

T or F: The exposure odds ratio compares those with the outcome (cases) to those without the outcome (controls)

Answer 13

True

Question 14

Outcome Odds Ratio Formula

Answer 14

𝑎𝑑 / 𝑏c

Question 15

The outcome odds in those with exposure is represented by ___ because it is the number of people with exposure and with outcome divided by the number of people with exposure and without the outcome.

Answer 15

a/b

Question 16

the outcome odds in those without exposure are represented by
___ because it is the number of people with outcome and without the exposure divided by the number of people without the outcome and without exposure.

Answer 16

c/d

Question 17

In the case of _______________, the interpretation compares the odds of outcome in the exposed group to the odds of outcome in the not exposed group.

Answer 17

outcome odds ratio

Question 18

The study design that collects data in this fashion is the ______________.

Answer 18

cohort study design

Question 19

the outcome odds ratio is used to ________________ in a cohort study design.

Answer 19

measure the association

Question 20

T or F: But remember that an odds ratio can be used in any study design, so the odds ratio must be flexible enough to reflect whatever design is used to collect the data.

Answer 20

True

Question 21

As a general rule, for a ______________ study, the ____________ is the measure of choice, but an outcome odds ratio can be used when
________ data are not available, such as in a retrospective cohort study, or because an investigator believes the odds ratio is more appropriate.

Answer 21

prospective cohort, relative risk, incidence

Question 21

As a general rule, for a ______________ study, the ____________ is the measure of choice, but an outcome odds ratio can be used when
________ data are not available, such as in a retrospective cohort study, or because an investigator believes the odds ratio is more appropriate.

Answer 21

prospective cohort, relative risk, incidence

Question 22

if the study design is a case control study, the only option for a measure association is the ________________

Answer 22

exposure odds ratio

Question 23

The odds that those with the outcome are exposed is xx.xx times as
likely as those without the outcome being exposed.

Answer 23

Exposure odds ratio

Question 24

The odds that those with the exposure have the outcome is xx.xx
times as likely as those without exposure have the outcome.

Answer 24

Outcomes odds ratio

Question 25

The ________________ is a measure of association that provides strength and direction of the association between existing exposure and outcome in the population.

Answer 25

prevalence ratio

Question 26

T or F: The prevalence ratio can be used in a cross sectional study or any study where the exposure data is prevalence.

Answer 26

False, outcome (exposure)

Question 27

T or F: A prevalence ratio has different interpretation as the relative risk and the odds ratio with respect to its null value of 1 and values greater or less than 1.

Answer 27

False, the same (different)

Question 28

The main difference is the prevalence ratio compares ___ prevalence rates.

Answer 28

two

Question 29

Prevalence Ratio Formula

Answer 29

𝑃𝑟𝑒𝑣𝑎𝑙𝑒𝑛𝑐𝑒 𝑟𝑎𝑡𝑖𝑜 = 𝑃𝑟𝑒𝑣𝑎𝑙𝑒𝑛𝑐𝑒 𝑟𝑎𝑡𝑒 𝑖𝑛 𝑡ℎ𝑒 𝑒𝑥𝑝𝑜𝑠𝑒𝑑 𝑔𝑟𝑜𝑢𝑝 / 𝑃𝑟𝑒𝑣𝑎𝑙𝑒𝑛𝑐𝑒 𝑟𝑎𝑡𝑒 𝑖𝑛 𝑡ℎ𝑒 𝑛𝑜𝑛𝑒𝑥𝑝𝑜𝑠𝑒𝑑 𝑔𝑟𝑜𝑢p

Question 30

The _________________, a measure of association between exposure and outcome, provides strength and direction using two incidence densities.

Answer 30

incidence density ratio

Question 31

An incidence density is a way to present disease occurrence using a ___________ that is comprised of person time and has some advantages over using rates.

Answer 31

denominator

Question 32

T or F: Incidence densities can be compared using a ratio to determine whether either of the two groups has a greater (or weaker) density of a disease. Incidence density ratios can be used as an indication of an increased or decreased risk of outcome.

Answer 32

True

Question 33

Incidence Density Ratio Formula

Answer 33

𝐼𝑛𝑐𝑖𝑑𝑒𝑛𝑐𝑒 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑟𝑎𝑡𝑖𝑜 = 𝐼𝑛𝑐𝑖𝑑𝑒𝑛𝑐𝑒 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑖𝑛 𝑡ℎ𝑒 𝑒𝑥𝑝𝑜𝑠𝑒𝑑 𝑔𝑟𝑜𝑢𝑝 / 𝐼𝑛𝑐𝑖𝑑𝑒𝑛𝑐𝑒 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑖𝑛 𝑡ℎ𝑒 𝑛𝑜𝑛 − 𝑒𝑥𝑝𝑜𝑠𝑒𝑑 𝑔𝑟𝑜𝑢p

Question 34

T or F: The incidence density ratio has the same interpretation as relative risk and the odds ratio.

Answer 34

True