# Kappa Statistic

Kappa Statistic:

Kappa statistic is a generic term for several similar measures of agreement used with categorical data . Typically it is used in assessing the degree to which two or more raters, examining the same data, agree when it comes to assigning the data to categories. for example, kappa might be used to assess the extent to which (1) radiologist analysis of an x-ray, (2) computer analysis of the same x-ray, and (3) biopsy agree in labeling a growth “malignant” or “benign.”

Suppose each object in a group of M objects is assigned to one of n categories. The categories are at nominal scale . For each object, such assignments are done by k raters.

The kappa measure of agreement is the ratio

 K = P(A) – P(E) 1 – P(E)

where P(A) is the proportion of times the k raters agree, and P(E) is the proportion of times the k raters are expected to agree by chance alone.

Complete agreement corresponds to K = 1 , and lack of agreement (i.e. purely random coincidences of rates) corresponds to K = 0 . A negative values of kappa would mean negative agreement – that is, the propensity of raters to avoid assignments made by other raters.

Browse Other Glossary Entries

## Test Yourself

Planning on taking an introductory statistics course, but not sure if you need to start at the beginning? Review the course description for each of our introductory statistics courses and estimate which best matches your level, then take the self test for that course. If you get all or almost all the questions correct, move on and take the next test.

### Data Analytics

Considering becoming adata scientist, customer analyst or our data science certificate program?

Analytics Quiz

Statistics Quiz

### Statistics

Looking at statistics for graduate programs or to enhance your foundational knowledge?

Statistics 1 Quiz

Regression Quiz

Regression Quiz

### Biostatistics

Entering the biostatistics field? Test your skill here.

Biostatistics Quiz

Statistics 2 Quiz

### Stay Informed

Our Blog

Read up on our latest blogs

Certificates

Courses

Find the right course for you