The Ratio of incidence of a disease among the exposed to the incidence among non-exposed is defined as
**Core Concept**
The underlying principle being tested is the concept of measuring the association between an exposure and an outcome, specifically in the context of epidemiology. This involves understanding **risk** and **incidence** and how they are used to quantify disease occurrence in populations.
**Why the Correct Answer is Right**
The correct answer is related to the definition of a specific epidemiological measure that quantifies the strength and direction of the association between an exposure and a disease. This measure is crucial for understanding the potential causal relationship between the exposure and the disease. The **incidence rate ratio** or **relative risk** is a measure that compares the incidence of a disease among those exposed to the incidence among those not exposed.
**Why Each Wrong Option is Incorrect**
**Option A:** This option does not accurately describe the comparison of disease incidence between exposed and non-exposed groups.
**Option B:** Similarly, this option does not correctly represent the ratio of incidence rates between exposed and non-exposed populations.
**Option C:** This option is also incorrect as it does not define the ratio of incidence among exposed to non-exposed.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that the **relative risk** or **incidence rate ratio** is a fundamental measure in epidemiology, helping to assess the strength of association between an exposure and a disease. It's essential for interpreting epidemiological studies.
**Correct Answer:** **Relative Risk**