Cohen’s Kappa Calculator
Medical example data 1 Medical example data 2With the Cohen’s Kappa Calculator numiqo, calculating Cohen’s Kappa statistic is quick and straightforward. Simply select two nominal variables, and the Kappa Calculator will generate the result instantly.
For calculating the weighted Cohen’s Kappa, you only need to select two ordinal variables.
Calculate Cohen's Kappa online
Cohen's Kappa is used to perform an inter-rater reliability analysis between the dependent samples Rater 1 and Rater 2. For this purpose, the Cohens Kappa is calculated, which is a measure of the agreement between two dependent categorical samples.
After Cohen's Kappa has been calculated, you can use the following table for interpretation (Landis & Koch (1977)).
| Kappa | Level of Agreement |
|---|---|
| > 0,8 | Almost perfect |
| > 0,6 | Substantial |
| > 0,4 | Moderate |
| > 0,2 | Fair |
| > 0 | Slight |
| < 0 | No agreement |
Cohen's kappa
The Cohens Kappa showed you how high the agreement between Rater 1 and Rater 2 is.
Cohen's kappa (often simply denoted as κ) is a statistic used to measure the agreement between two raters who each classify items into categorical classes, beyond what is expected by chance. It's especially useful when considering that agreement might occur just by chance .Mathematically, it's given by the formula:
kappa = (PO - PE)/(1 - PE)
- PO is the observed proportion of agreement.
- PE is the expected proportion of agreement by chance.
The value of kappa ranges from -1 to 1:
- A value of 1 indicates perfect agreement.
- A value of 0 indicates agreement no better than chance.
- A value less than 0 indicates agreement less than chance.
Standard error Cohen's kappa
The standard error for Cohen's kappa is calculated according to Cohen (1960) with the following formula calculated
Calculate weighted Cohen's Kappa
Cohen's Kappa takes into account the agreement between two raters, but degree of agreement is not considered. However, if the variables are ordinal, it is desirable to include the rank in the calculation. This is exactly what is done in weighted Cohen's Kappa.
If you click on two ordinal variables, the weighted Cohen's Kappa is automatically calculated. You can then choose whether you want to have a linear or a quadratic weighting.
Kappa Online Calculator
Cohens Kappa is calculated in statistics to determine interrater reliability. With numiqo you can calculate either the Cohen’s Kappa or the Fleiss Kappa online. If you want to calculate the Cohen's Kappa, simply select 2 categorical variables, if you want to calculate the Fleiss Kappa, simply select three variables.
References
Cohen, Jacob. 1960. 'A Coefficient of Agreement for Nominal Scales'. Educational and Psychological Measurement. Vol. 20, No. 1, 37-46.