equate (version 0.1-1)

freqtab: Frequency Tabulation

Description

This function creates a frequency table for a vector, or vectors, of scores.

Usage

freqtab(x, xscale, v, vscale, addclass = FALSE)

Arguments

x

vector of scores (one per examinee) for form X

xscale

the score scale for form X, as a vector

v

vector of scores (one per examinee) for form X examinees on the anchor test

vscale

the anchor test score scale, as a vector

addclass

logical. When TRUE (and v is missing) x and xscale are simply combined as a matrix of class freqtab

Value

• In the univariate case (i.e., no anchor is specified) a 2-column matrix is returned, where column 1 contains the score scale and column 2 the frequency for each scale value. In the bivariate case a 3-column matrix is returned where columns 1 and 2 contain all combinations of form X score scale points (in column 1) and score scale points on the anchor test (in column 2), and column 3 contains the total number of examinees obtaining the corresponding score combination.

Details

If x is a vector of total scores, values are factored with levels = xscale. This ensures that unobtained scores (i.e., scores not in x) will still be represented in the tabulation. If x is a vector of frequencies, with one value for each score scale point provided in xscale, and addclass=TRUE, the function serves to simply change the class of x to freqtab.

See Also

table

Examples

set.seed(2005)
x1 <- round(rnorm(1000,100,10))
x1scale <- 70:130
freqtab(x1,x1scale)

x2 <- ACTmath[,2]
x2scale <- ACTmath[,1]
freqtab(x2,x2scale,addclass=TRUE)

xscale <- 0:36
vscale <- 0:12
freqtab(KBneat$x[,1],xscale,KBneat$x[,2],vscale)