1. What is Prevalence?

Prevalence refers to the proportion of a population found to have a condition at a specific time. It is calculated as the product of incidence rate and average duration of the disease.

2. How Does the Calculator Work?

The calculator uses the prevalence formula:

Where:

• \( Prevalence \) — Proportion of population affected (decimal)
• \( Incidence \) — Rate of new cases per unit time
• \( Duration \) — Average duration of the condition in the same time units

Explanation: This formula assumes steady-state conditions where incidence and duration remain constant over time.

3. Importance of Prevalence Calculation

Details: Prevalence estimates are essential for public health planning, resource allocation, and understanding disease burden in populations.

4. Using the Calculator

Tips: Enter incidence rate (new cases per unit time) and average duration (in the same time units). Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between prevalence and incidence?
A: Incidence measures new cases over time, while prevalence measures existing cases at a point in time.

Q2: What time units should I use?
A: Use consistent units (e.g., if incidence is per year, duration should be in years).

Q3: When is this formula not accurate?
A: When incidence or duration changes rapidly, or for diseases with very short or very long durations.

Q4: Can prevalence be greater than 1?
A: Yes, if expressed as count rather than proportion, but typically kept between 0-1 when expressed as proportion.

Q5: How does mortality affect prevalence?
A: Higher mortality reduces prevalence by shortening disease duration.