irr (version 0.70)

kripp.alpha: 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")

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")