Incidence of a disease in a population of 30,000 and 300 new cases is?
## **Core Concept**
The core concept being tested here is the calculation of **incidence rate** or **incidence proportion** of a disease in a population. Incidence rate refers to the number of new cases of a disease that occur within a specified period among a population at risk.
## **Why the Correct Answer is Right**
To calculate the incidence proportion (or rate), we use the formula: (Number of new cases / Population at risk) × 100. Given that there are 300 new cases in a population of 30,000, we substitute these values into the formula: (300 / 30,000) × 100 = 1%. This matches option **C. 1%**, making it the correct answer. This calculation provides a measure of the risk of developing the disease within the population over a specific period.
## **Why Each Wrong Option is Incorrect**
- **Option A:** Without a specific percentage or rate provided, it's impossible to directly assess its correctness, but it's not 1%, which we've determined is correct.
- **Option B:** Similarly, without a specific value, we can't directly calculate, but it's stated as incorrect in favor of option C.
- **Option D:** This option suggests a much higher rate (10%), which doesn't align with our calculation of 1%.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **incidence** reflects the number of **new cases** that develop in a specified time period among a population at risk, whereas **prevalence** reflects the total number of cases (new and existing) at a specific point in time. Understanding the distinction between these epidemiological measures is crucial for interpreting disease patterns and planning healthcare interventions.
## **Correct Answer:** C. 1%