This calculator is designed for researchers and statisticians to compute Cohen's Kappa, a statistical measure of inter-rater reliability. Use it to understand the level of agreement between two raters beyond chance.
All calculations are based on the standard formula for Cohen's Kappa, which is widely accepted in statistical analysis for measuring inter-rater reliability.
The formula used is: \( \kappa = \frac{{P_o - P_e}}{{1 - P_e}} \) where \( P_o \) is the relative observed agreement among raters, and \( P_e \) is the hypothetical probability of chance agreement.
Suppose two raters evaluated 100 cases, and they agreed on 80 of those. The observed agreement (Po) is 0.8. Assuming chance agreement (Pe) is 0.6, the Cohen's Kappa would be calculated as follows: \( \kappa = \frac{{0.8 - 0.6}}{{1 - 0.6}} = 0.5 \).
A Kappa value of 1 indicates perfect agreement between raters.
Yes, a negative Kappa value indicates less agreement than expected by chance.
Chance agreement is calculated based on the distribution of categorical ratings by each rater.
Cohen's Kappa is suitable for categorical, nominal data. For ordinal data, weighted Kappa might be more appropriate.
Kappa can be affected by prevalence and bias, and it assumes that raters are independent.