kripp.alpha {irr}R Documentation

calculate Krippendorff's alpha reliability coefficient

Description

calculates the alpha coefficient of reliability proposed by Krippendorff

Usage

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

Arguments

x classifier x object matrix of classifications or scores
method data level of x

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).
cm 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.

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=4)
 # 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 0.82 Index]