equate (version 0.1-1)

cov.freqtab: Covariance of a Frequency Table

Description

This function computes the covariance of a frequency table of class freqtab

Usage

cov.freqtab(x)

Arguments

x

score distribution of class freqtab for form X. Under the random groups design (i.e., no anchor test) x will contain the score scale in column 1, and the number of examinees ob

Value

• Returns the variance, in the univariate case, and the covariance for the bivariate

See Also

freqtab, mean.freqtab

Examples

set.seed(2005)
x <- round(rnorm(1000,100,10))
xscale <- 70:130
xtab <- freqtab(x,xscale)
cov.freqtab(xtab); var(x)

yscale <- 0:36
vscale <- 0:12
ny <- freqtab(KBneat$y[,1],yscale,KBneat$y[,2],vscale)
cov.freqtab(ny); cov(KBneat$y[,1],KBneat$y[,2])