Prevalence Ratio Formula:
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The Prevalence Ratio (PR) compares the prevalence of an outcome in an exposed group to its prevalence in an unexposed group. It's commonly used in cross-sectional studies to measure the strength of association between exposure and outcome.
The calculator uses the Prevalence Ratio formula:
Where:
Interpretation:
Details: Prevalence Ratio is particularly useful in pediatric studies where measuring incidence may be challenging. It helps identify potential risk factors for childhood conditions and evaluate intervention effectiveness.
Tips: Enter prevalence values as decimals between 0 and 1 (e.g., 0.25 for 25%). The unexposed prevalence must be greater than zero.
Q1: How is PR different from odds ratio?
A: PR uses prevalence directly, while odds ratio uses odds. PR is more intuitive for common outcomes (>10% prevalence).
Q2: When should PR be used instead of risk ratio?
A: PR is used in cross-sectional studies, while risk ratio is for cohort studies. Both measure association but in different study designs.
Q3: What are limitations of PR?
A: PR can't establish temporal relationship (cross-sectional design) and may be affected by differential survival in exposed/unexposed groups.
Q4: How to interpret PR for childhood conditions?
A: In children, PR > 1.5 often suggests meaningful association, but clinical judgment is needed based on condition and population.
Q5: Can PR be used for public health decisions?
A: Yes, PR helps identify high-risk groups for targeted interventions, especially in pediatric populations.