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

Rate ratios are closely related to risk ratios, but they are computed as the ratio of the incidence rate in an exposed group divided by the incidence rate in an unexposed (or less exposed) comparison group.

What is the difference between incidence rate and risk?

– Incidence risk is a measure of disease occurrence over a defined period of time. It is a proportion, therefore takes values from 0 to 1 (0\% to 100\%). – Incidence rate takes into account the time an individual is at risk of disease.

What is an incident rate ratio?

In epidemiology, a rate ratio, sometimes called an incidence density ratio or incidence rate ratio, is a relative difference measure used to compare the incidence rates of events occurring at any given point in time. The same time intervals must be used for both incidence rates.

Why are odds ratio and risk ratio different?

The odds ratio (OR) is the ratio of odds of an event in one group versus the odds of the event in the other group. 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 is the rate difference?

Analogous to the risk difference, the rate difference is calculated by subtracting the incidence rate in the unexposed group (or least exposed group) from the incidence rate in the group with the exposure. However, a rate difference is based on subtraction of incidence rates, so the units are retained.

How do you interpret incident rate ratio?

IRR Equal to 1: This indicates that the incident rate is equal among those in an exposed group and those in an unexposed group. For example, if smokers developed lung cancer at a rate of 7 per 100 person-years and non-smokers developed lung cancer at a rate of 7 per 100 person-years, then the IRR would be 7/7 = 1.

How do you explain risk differences?

The risk difference is straightforward to interpret: it describes the actual difference in the observed risk of events between experimental and control interventions; for an individual it describes the estimated difference in the probability of experiencing the event.

Are odds ratio and likelihood ratio the same?

Likelihood ratio is a ratio of odds (but not the usual odds ratio)