kripp.alpha: calculate Krippendorff's alpha reliability coefficient

In irr: Various Coefficients of Interrater Reliability and Agreement

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") 

Example output

Loading required package: lpSolve
 Krippendorff's alpha

 Subjects = 12 
   Raters = 4 
    alpha = 0.743 
 Krippendorff's alpha

 Subjects = 12 
   Raters = 4 
    alpha = 0.815 
 Krippendorff's alpha

 Subjects = 12 
   Raters = 4 
    alpha = 0.849 
 Krippendorff's alpha

 Subjects = 12 
   Raters = 4 
    alpha = 0.797 

irr documentation built on May 2, 2019, 8:50 a.m.