1. What is Cohen's Kappa?

Cohen's Kappa is a statistical measure that assesses interrater reliability for categorical items. It measures the agreement between two raters while accounting for the possibility of the agreement occurring by chance.

2. How Does the Calculator Work?

The calculator uses Cohen's Kappa formula:

Where:

• \( P_o \) — Observed agreement proportion (unitless)
• \( P_e \) — Expected agreement proportion (unitless)

Explanation: The formula calculates the degree of agreement between two raters beyond what would be expected by chance alone.

3. Importance of Interrater Reliability

Details: Interrater reliability is crucial in research and clinical settings to ensure consistency and objectivity in measurements and classifications made by different observers.

4. Using the Calculator

Tips: Enter the observed agreement proportion (Po) and expected agreement proportion (Pe) as values between 0 and 1. Both values must be valid proportions.

5. Frequently Asked Questions (FAQ)

Q1: What does Cohen's Kappa value indicate?
A: Kappa values range from -1 to 1, where 1 indicates perfect agreement, 0 indicates agreement equivalent to chance, and negative values indicate agreement worse than chance.

Q2: How is Kappa interpreted?
A: Generally, κ ≤ 0: no agreement, 0.01-0.20: slight, 0.21-0.40: fair, 0.41-0.60: moderate, 0.61-0.80: substantial, 0.81-1.00: almost perfect agreement.

Q3: When should Cohen's Kappa be used?
A: It's appropriate for categorical data when two raters each classify items into mutually exclusive categories.

Q4: What are the limitations of Cohen's Kappa?
A: Kappa can be affected by prevalence and bias, and may not be appropriate for ordinal data or when there are more than two raters.

Q5: Are there alternatives to Cohen's Kappa?
A: Yes, alternatives include Fleiss' Kappa (multiple raters), Weighted Kappa (ordinal data), and Intraclass Correlation Coefficient (continuous data).