gwet.ac1.raw: Gwet's AC1/AC2 agreement coefficient among multiple raters...

In irrCAC: Computing Chance-Corrected Agreement Coefficients (CAC)

Description

Gwet's AC1/AC2 agreement coefficient among multiple raters (2, 3, +) when the input data represent the raw ratings reported for each subject and each rater.

Usage

gwet.ac1.raw(ratings, weights = "unweighted", categ.labels = NULL,
  conflev = 0.95, N = Inf)

Arguments

ratings	An nxr matrix / data frame of ratings where each column represents one rater and each row one subject.
weights	is a mandatory parameter that is either a string variable or a matrix. The string describes one of the predefined weights and must take one of the values ("quadratic", "ordinal", "linear", "radical", "ratio", "circular", "bipolar"). If this parameter is a matrix then it must be a square matri qxq where q is the number of posssible categories where a subject can be classified. If some of the q possible categories are not used, then it is strobgly advised to specify the complete list of possible categories as a vector in parametr categ.labels. Otherwise, the program may not work.
categ.labels	An optional vector parameter containing the list of all possible ratings. It may be useful in case some of the possibe ratings are not used by any rater, they will still be used when calculating agreement coefficients. The default value is NULL. In this case, only categories reported by the raters are used in the calculations.
conflev	An optional parameter representing the confidence level associated with the confidence interval. Its default value is 0.95.
N	An optional parameter representing the population size (if any). It may be use to perform the final population correction to the variance. Its default value is infinity.

Value

A data list containing 3 objects: (1) a one-row data frame containing various statistics including the requested agreement coefficient, (2) the weight matrix used in the calculations if any, and (3) the categories used in the analysis. These could be categories reported by the raters, or those that were available to the raters whether they used them or not. The output data frame contains the following variables: "coeff.name" (coefficient name), "pa" (the percent agreement), "pe" (the percent chance agreement), coeff.val (the agreement coefficient estimate-AC1 or AC2), "coeff.se" (the standard error), "conf.int" (AC1/AC2 confidence interval), "p.value" (Gwet AC1/AC2 p-value), "w.name"(the weights' identification).

References

Gwet, K. L. (2008). “Computing inter-rater reliability and its variance in the presence of high agreement." British Journal of Mathematical and Statistical Psychology, 61, 29-48.

Examples

#The dataset "cac.raw4raters" comes with this package. Analyze it as follows:
cac.raw4raters
gwet.ac1.raw(cac.raw4raters) #AC1 coefficient, precision measures, weights & categories
gwet.ac1.raw(cac.raw4raters)$est #Yields AC1 coefficient with precision measures
ac1 <- gwet.ac1.raw(cac.raw4raters)$est$coeff.val #Yields AC1 coefficient alone.
ac1
gwet.ac1.raw(cac.raw4raters, weights = "quadratic") #AC2 coefficient with quadratic wts

Example output

   Rater1 Rater2 Rater3 Rater4
1       1      1     NA      1
2       2      2      3      2
3       3      3      3      3
4       3      3      3      3
5       2      2      2      2
6       1      2      3      4
7       4      4      4      4
8       1      1      2      1
9       2      2      2      2
10     NA      5      5      5
11     NA     NA      1      1
12     NA     NA      3     NA
$est
  coeff.name        pa        pe coeff.val coeff.se  conf.int     p.value
1        AC1 0.8181818 0.1903212   0.77544  0.14295 (0.461,1) 0.000208721
      w.name
1 unweighted

$weights
     [,1] [,2] [,3] [,4] [,5]
[1,]    1    0    0    0    0
[2,]    0    1    0    0    0
[3,]    0    0    1    0    0
[4,]    0    0    0    1    0
[5,]    0    0    0    0    1

$categories
[1] 1 2 3 4 5

  coeff.name        pa        pe coeff.val coeff.se  conf.int     p.value
1        AC1 0.8181818 0.1903212   0.77544  0.14295 (0.461,1) 0.000208721
      w.name
1 unweighted
[1] 0.77544
$est
  coeff.name        pa        pe coeff.val coeff.se  conf.int      p.value
1        AC2 0.9753788 0.7137044     0.914  0.10396 (0.685,1) 2.634438e-06
     w.name
1 quadratic

$weights
       [,1]   [,2]   [,3]   [,4]   [,5]
[1,] 1.0000 0.9375 0.7500 0.4375 0.0000
[2,] 0.9375 1.0000 0.9375 0.7500 0.4375
[3,] 0.7500 0.9375 1.0000 0.9375 0.7500
[4,] 0.4375 0.7500 0.9375 1.0000 0.9375
[5,] 0.0000 0.4375 0.7500 0.9375 1.0000

$categories
[1] 1 2 3 4 5

irrCAC documentation built on Sept. 23, 2019, 5:05 p.m.