Kappa {vcd} | R Documentation

## Cohen's Kappa and Weighted Kappa

### Description

Computes two agreement rates: Cohen's kappa and weighted kappa, and confidence bands.

### Usage

    Kappa(x, weights = c("Equal-Spacing", "Fleiss-Cohen"))

### Arguments

`x` | a confusion matrix.
`weights` | either one of the character strings given in the default value, or a user-specified matrix with same dimensions as `x`.

### Details

Cohen's kappa is the diagonal sum of the (possibly weighted) relative frequencies, corrected for expected values and standardized by its maximum value. The equal-spacing weights are defined by 1 - abs(i - j) / (r - 1), r number of colums/rows, and the Fleiss-Cohen weights by 1 - abs(i - j)^2 / (r - 1)^2. The latter one attaches greater importance to near disagreements.

### Value

An object of class `"Kappa"` with three components:

`Unweighted` | numeric vector of length 2 with the kappa statistic (`value` component), along with Approximate Standard Error (`ASE` component)
`Weighted` | idem for the weighted kappa.
`Weights` | numeric matrix with weights used.

### Note

The `summary` method also prints the weights.

There is a `confint` method for computing approximate confidence intervals.

### Author(s)

David Meyer David.Meyer@R-project.org

### References

Jacob Cohen (1960), A coefficient of agreement for nominal scales. Educational and Psychological Measurement, 20, 37–46.

B. S. Everitt, (1968), Moments of statistics kappa and weighted kappa. The British Journal of Mathematical and Statistical Psychology, 21, 97–103.

### See Also

`agreementplot`, `confint`

### Examples

    data(SexualFun)
    Kappa(SexualFun)

[Package vcd version 0.9-6 Index]