kripp.alpha {irr}R Documentation

Krippendorff's alpha reliability coefficient

Description

Calculates the alpha coefficient of reliability proposed by Krippendorff (1980).

Usage

 kripp.alpha(x, method = c("nominal", "ordinal", "interval", "ratio"))

Arguments

x n*m matrix or dataframe, n objects m raters.
method data level of ratings, you can specify just the initial letter.

Value

A list with class '"irrlist"' containing the following components:

$method a character string describing the method.
$subjects the number of data objects.
$raters the number of raters.
$irr.name a character string specifying the name of the coefficient.
$value value of alpha.
$stat.name here "nil" as there is no test statistic.
$statistic the value of the test statistic (NULL).
$p.value the probability of the test statistic (NULL).
coincidence.matrix the concordance/discordance matrix used in the calculation of alpha
data.values a character vector of the unique data values
levx the unique values of the ratings
nmatchval the count of matches, used in calculation
data.level the data level of the ratings ("nominal","ordinal", "interval","ratio")

Note

Krippendorff's alpha coefficient is particularly useful where the level of measurement of classification data is higher than nominal or ordinal.

Author(s)

Jim Lemon

References

Krippendorff, K. (1980) Content analysis: An introduction to its methodology. Beverly Hills, CA: Sage.

See Also

icc, meancor, kendall, kappam.fleiss

Examples

 # the "C" data from Krippendorff
 nmm <- matrix(c( 1, 1,NA, 1, 2, 2, 3, 2, 3, 3, 3, 3,
                  3, 3, 3, 3, 2, 2, 2, 2, 1, 2, 3, 4,
                  4, 4, 4, 4, 1, 1, 2, 1, 2, 2, 2, 2,
                 NA, 5, 5, 5,NA,NA, 1, 1,NA,NA, 3,NA),nrow=12,byrow=TRUE)
 # first assume the default nominal classification
 kripp.alpha(nmm)
 # now use the same data with the other three methods
 kripp.alpha(nmm, "ordinal")
 kripp.alpha(nmm, "interval")
 kripp.alpha(nmm, "ratio") 

[Package irr version 0.70 Index]