DescTools (version 0.99.8.1)

KendallW: Kendall's Coefficient of Concordance W

Description

Computes Kendall's coefficient of concordance as an index of interrater reliability of ordinal data. The coefficient could be corrected for ties within raters.

Usage

KendallW(ratings, correct = FALSE, test = FALSE)

Arguments

ratings

n*m matrix or dataframe, n subjects m raters.

correct

a logical indicating whether the coefficient should be corrected for ties within raters.

test

a logical indicating whether the test statistic and p-value should be reported.

Value

• Either a single value if test is set to FALSE or else a list with class htest containing the following components:
• statistic
  the value of the chi-square statistic.
• p.value
  the p-value for the test.
• method
  the character string Kendall's coefficient of concordance W.
• data.name
  a character string giving the name(s) of the data.
• estimate
  the coefficient of concordance.
• parameter
  the degrees of freedom df, the number of subjects examined and the number of raters.

Details

Missing data are omitted in a listwise way. Kendall's W should be corrected for ties if raters did not use a true ranking order for the subjects. A test for the significance of Kendall's W is only valid for large samples.

References

Kendall, M.G. (1948) Rank correlation methods. London: Griffin.

See Also

cor

Examples

anxiety <- data.frame(rater1=c(3,3,3,4,5,5,2,3,5,2,2,6,1,5,2,2,1,2,4,3),
                      rater2=c(3,6,4,6,2,4,2,4,3,3,2,3,3,3,2,2,1,3,3,4),
                      rater3=c(2,1,4,4,3,2,1,6,1,1,1,2,3,3,1,1,3,3,2,2))

KendallW(anxiety, TRUE)

# with test results
KendallW(anxiety, TRUE, test=TRUE)