kra: Krippendorff's alpha

In rel: Reliability Coefficients

Description

Calculates Krippendorff's alpha as an index of agreement for nominal, ordinal, interval, or ratio scale data.

Usage

kra(data = NULL, weight = c("nominal","ordinal","interval","ratio"), 
    conf.level = 0.95, R = 0)

Arguments

data	A matrix with n subjects and m observations (n*m matrix).
weight	Data scale of ratings specified as "nominal, "ordinal", "interval", or "ratio".
conf.level	Confidence level of the interval.
R	Number of bootstrap replicates used to estimate the confidence interval.

Details

Krippendorff's alpha is a measure of observed disagreement relative to disagreement expected by chance which has the advantages of being applicable to multiple raters, different scale metrics, and incomplete data sets (Krippendorff, 2004 p.221-243). Noteworthy is that alpha by definition is zero when the observed disagreement equals the expected disagreement (i.e., when variance is absent which is the case for perfect agreement). The confidence interval of alpha is derived via bootstrapping because its distribution is unknown.

Value

method	Analysis name
raters	Number of raters
sample	Sample size
na	Percent of missing values
est	Point estimate
lb	Lower confidence boundary
ub	Upper confidence boundary
cont.table	contingency table
data	analyzed data

Author(s)

Riccardo Lo Martire

References

Krippendorff, K. (2004). Content Analysis: An Introduction to Its Methodology. Thousand Oaks, CA: Sage.

Examples

#Sample data: 4 raters, 12 subjects, and 5 ordinal scale response categories.
data <- cbind(rbind(1,2,3,3,2,1,4,1,2,NA,NA,NA),
              rbind(1,2,3,3,2,2,4,1,2,5,NA,3),
              rbind(NA,3,3,3,2,3,4,2,2,5,1,NA),
              rbind(1,2,3,3,2,4,4,1,2,5,1,NA))

#Krippendorff's alpha for ordinal scale data
kra(data = data, weight = "ordinal", conf.level = 0.95, R = 0)

Example output

Call:
kra(data = data, weight = "ordinal", conf.level = 0.95, R = 0)

      Estimate LowerCB UpperCB
Const  0.81539      NA      NA

Confidence level = 95%
Observations = 4
Sample size = 12

rel documentation built on March 3, 2020, 9:07 a.m.