# Often asked: When to use odds ratio vs relative risk?

## Is rate ratio the same as relative risk?

A risk ratio (RR), also called relative risk, compares the risk of a health event (disease, injury, risk factor, or death) among one group with the risk among another group.

## What is the difference between risk ratio and rate ratio?

Rate ratio: ratio of the rate of an event in one group (exposure or intervention) to that in another group (control). Risk ratio: ratio of the risk of an event in one group (exposure or intervention) to that in another group (control).

## Why do we use odds ratio for Case Control?

The odds ratio is calculated using the number of case-patients who did or did not have exposure to a factor (such as a particular food) and the number of controls who did or did not have the exposure. The odds ratio tells us how much higher the odds of exposure are among case-patients than among controls.

## Why are the relative risk and odds ratio approximately equal?

It is assumed that, if the prevalence of the disease is low, then the odds ratio approaches the relative risk. Case control studies are relatively inexpensive and less time-consuming than cohort studies. In this case the odds ratio (OR) is equal to 16 and the relative risk (RR) is equal to 8.65.

## What does a risk ratio of 0.75 mean?

The interpretation of the clinical importance of a given risk ratio cannot be made without knowledge of the typical risk of events without treatment: a risk ratio of 0.75 could correspond to a clinically important reduction in events from 80% to 60%, or a small, less clinically important reduction from 4% to 3%.

## What does a relative risk of 2.5 mean?

0.1 = 2.5. This means that. those in the control group were 2.5 times more likely to die than those in the treatment group. The relative risk is interpreted in terms of the risk of the group in the numerator.

## How do you interpret incidence risk ratio?

In general:

1. If the risk ratio is 1 (or close to 1), it suggests no difference or little difference in risk (incidence in each group is the same).
2. A risk ratio > 1 suggests an increased risk of that outcome in the exposed group.
3. A risk ratio < 1 suggests a reduced risk in the exposed group.

## How do you interpret odds ratio?

Odds Ratio is a measure of the strength of association with an exposure and an outcome.

1. OR > 1 means greater odds of association with the exposure and outcome.
2. OR = 1 means there is no association between exposure and outcome.
3. OR < 1 means there is a lower odds of association between the exposure and outcome.

## How do you interpret odds ratio and relative risk?

RELATIVE RISK AND ODDS RATIO

An RR (or OR) more than 1.0 indicates an increase in risk (or odds) among the exposed compared to the unexposed, whereas a RR (or OR) <1.0 indicates a decrease in risk (or odds) in the exposed group.

## What does an odds ratio of 2.5 mean?

If odds ratio is 2.5, then there is a 2.5 times higher likelihood of having the outcome compared to the comparison group. Here the odds ratio would be 0.80. The odds ratio also shows the strength of the association between the variable and the outcome.

## Can you use odds ratio in cohort study?

In an RCT or cohort study, the odds ratio can be calculated as well. The odds ratio is then defined as the odds of the outcome in the treated patients divided by the odds of the outcome in the untreated patients.

## How do you figure out odds?

Odds, are given as (chances for success): (chances against success) or vice versa. If odds are stated as an A to B chance of winning then the probability of winning is given as PW = A / (A + B) while the probability of losing is given as PL = B / (A + B).

## What does Relative Risk tell you?

Relative risk is the ratio of the risks for an event for the exposure group to the risks for the non-exposure group. Thus relative risk provides an increase or decrease in the likelihood of an event based on some exposure.

## What does an odds ratio of 0.5 mean?

An odds ratio of 0.5 would mean that the exposed group has half, or 50%, of the odds of developing disease as the unexposed group. In other words, the exposure is protective against disease.

## Is odds ratio a measure of risk?

The odds ratio is a common measure of risk but its interpretation may be hazardous. The risk ratio is a ratio of probabilities, which are themselves ratios. The numerator of a probability is the number of cases with the outcome, and the denominator is the total number of cases.