irr (version 0.70)

rater.bias: Coefficient of rater bias

Description

Calculates a coefficient of systematic bias between two raters.

Usage

rater.bias(x)

Arguments

x

c x c classification matrix or 2 x n or n x 2 matrix of classification scores into c categories.

Value

• method
  Name of the method
• subjects
  Number of subjects
• raters
  Number of raters (2)
• irr.name
  Name of the coefficient: ratio of triangular off-diagnonal sums
• value
  Value of the coefficient
• stat.name
  Name of the test statistic
• statistic
  Value of the test statistic
• p.value
  the probability of the df 1 Chi-square variable

Details

rater.bias calculates a reliability coefficient for two raters classifying n objects into any number of categories. It will accept either a c x c classification matrix of counts of objects falling into c categories or a 2 x n or n x 2 matrix of classification scores. \crThefunction returns the absolute value of the triangular off-diagnonal sum ratio of the cxc classification table and the corresponding test statistic. A systematic bias between raters can be assumed when the ratio substantially deviates from 0.5 while yielding a significant Chi-squared statistic.

References

Bishop Y.M.M., Fienberg S.E., & Holland P.W. (1978) Discrete multivariate analysis: theory and practice. Cambridge, Massachusetts: MIT Press.

See Also

mcnemar.test

Examples

# fake a 2xn matrix of three way classification scores
 ratings <- matrix(sample(1:3,60,TRUE), nrow=2)
 rater.bias(ratings)

 # Example from Bishop, Fienberg & Holland (1978), Table 8.2-1
 data(vision)
 rater.bias(vision)