betafunctions (version 1.9.0)

ccStats: Classification Consistency Statistics.

Description

Provides a set of statistics often used for conveying information regarding the consistency of classifications based on tests.

Usage

ccStats(ii, ij, ji, jj)

Value

A list of classification consistency statistics. Specifically, the coefficient of consistent classification (p), the coefficient of consistent classification by chance (p_c), the proportion of positive classifications due to chance (p_c_pos), the proportion of negative classifications due to chance (p_c_neg), and Cohen's Kappa coefficient.

Arguments

ii

The frequency or rate of consistent classifications into category "i".

ij

The frequency or rate of inconsistent classifications into categories "i" and "j".

ji

The frequency or rate of inconsistent classifications into categories "j" and "i".

jj

The frequency or rate of consistent classifications into category "j".

References

Hanson, Bradley A. (1991). Method of Moments Estimates for the Four-Parameter Beta Compound Binomial Model and the Calculation of Classification Consistency Indexes. American College Testing.

Examples

# Generate some fictional data. Say, 1000 individuals take a test with a
# maximum score of 100 and a minimum score of 0.
set.seed(1234)
testdata <- rbinom(1000, 100, rBeta.4P(1000, .25, .75, 5, 3))
hist(testdata, xlim = c(0, 100))

# Suppose the cutoff value for attaining a pass is 50 items correct, and
# that the reliability of this test was estimated to 0.7. First, compute the
# estimated consistency matrix using LL.CA():
cmat <- LL.CA(x = testdata, reliability = .7, cut = 50, min = 0,
max = 100)$consistencymatrix

# To estimate and retrieve consistency statistics using ccStats(),
# feed it the appropriate entries of the consistency matrix.
ccStats(ii = cmat["i", "i"], ij = cmat["i", "j"],
ji = cmat["j", "i"], jj = cmat["j", "j"])