What Is the Odds Ratio Calculator?
An odds ratio calculator determines relative odds of exposure occurrence in retrospective clinical research.
How Does the Odds Ratio Calculator Work?
Computes the cross-product ratio (ad)/(bc) and derives Woolfs log-linear confidence boundaries.
Odds Ratio Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
OR = (a × d) ÷ (b × c) · SE(ln OR) = √(1/a + 1/b + 1/c + 1/d)
Cross-multiplies contingency cells and evaluates asymptotic standard error in log space.
How to Use the Odds Ratio Calculator
- Enter the four cell counts representing exposed and unexposed cases and controls.
Step-by-Step Example Calculation
Cases (40/20) vs Controls (30/70)
Input Values:
casesExposed:40
casesUnexposed:20
controlsExposed:30
controlsUnexposed:70
Understanding Your Result
Displays estimated odds ratio, confidence interval, and individual odds for cases and controls.
Factors That Affect the Result
- Selection bias in control recruitment and recall bias in retrospective histories.
When Should You Use This Calculator?
- Case-control observational studies, outbreak tracing, and logistic regression evaluation.
Assumptions & Limitations
- Requires non-zero cell frequencies for standard asymptotic confidence intervals.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Standard Woolf formulation for odds ratio estimation.