Odds Ratio Flashcards
T or F: If the probability of a success > p, then the odds in favor of success = p/(1 βp). 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.
False, success = p
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 _____________.
available, relative risk, not available, odds ratio (OR)
odds ratio can be used to ________________ in any study design. This makes the odds ratio a very widely used _________________.
measure associations, measure of association
__________ is a measure association that provides the strength and direction of the association between exposure and outcome in a population.
odds ratio
T or F: the results of the odds ratio are interpreted in the same
manner as the relative risk.
True
An odds ratio equal to 1 indicates that there is ___________between exposure and outcome in the observed populations.
no relationship
An odds ratio greater than 1 indicates a
_____________ between exposure and outcome
positive association
an odds ratio less than 1 indicates a
__________________ between exposure and outcome
negative association
Exposure Odds Ratio Formula
π/π / π/d
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.
a/c
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.
b/d
traditional odd ratio formula
ππ / πc
T or F: The exposure odds ratio compares those with the outcome (cases) to those without the outcome (controls)
True
Outcome Odds Ratio Formula
ππ / πc
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.
a/b
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.
c/d
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.
outcome odds ratio
The study design that collects data in this fashion is the ______________.
cohort study design
the outcome odds ratio is used to ________________ in a cohort study design.
measure the association
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.
True
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.
prospective cohort, relative risk, incidence
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.
prospective cohort, relative risk, incidence
if the study design is a case control study, the only option for a measure association is the ________________
exposure odds ratio
The odds that those with the outcome are exposed is xx.xx times as
likely as those without the outcome being exposed.
Exposure odds ratio
The odds that those with the exposure have the outcome is xx.xx
times as likely as those without exposure have the outcome.
Outcomes odds ratio
The ________________ is a measure of association that provides strength and direction of the association between existing exposure and outcome in the population.
prevalence ratio
T or F: The prevalence ratio can be used in a cross sectional study or any study where the exposure data is prevalence.
False, outcome (exposure)
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.
False, the same (different)
The main difference is the prevalence ratio compares ___ prevalence rates.
two
Prevalence Ratio Formula
ππππ£ππππππ πππ‘ππ = ππππ£ππππππ πππ‘π ππ π‘βπ ππ₯πππ ππ ππππ’π / ππππ£ππππππ πππ‘π ππ π‘βπ πππππ₯πππ ππ ππππ’p
The _________________, a measure of association between exposure and outcome, provides strength and direction using two incidence densities.
incidence density ratio
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.
denominator
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.
True
Incidence Density Ratio Formula
πΌππππππππ ππππ ππ‘π¦ πππ‘ππ = πΌππππππππ ππππ ππ‘π¦ ππ π‘βπ ππ₯πππ ππ ππππ’π / πΌππππππππ ππππ ππ‘π¦ ππ π‘βπ πππ β ππ₯πππ ππ ππππ’p
T or F: The incidence density ratio has the same interpretation as relative risk and the odds ratio.
True
