summary.meqc: Summarizing Bisector Equating Coefficients

In equateIRT: IRT Equating Methods

Summarizing Bisector Equating Coefficients

Description

summary method for class meqc.

Usage

## S3 method for class 'meqc'
summary(object, ...)

## S3 method for class 'summary.meqc'
print(x, ...)

Arguments

object	an object of the class meqc returned by function bisectorec.
x	an object of class summary.meqc, a result of a call to summary.meqc.
...	further arguments passed to or from other methods.

Value

The function summary.meqc returns a list with components

link	character vector with names of equated forms.
method	the equating method used.
coefficients	list of data frames containing Path, Estimate and StdErr of direct, chain and bisector equating coefficients.

Author(s)

Michela Battauz

See Also

bisectorec, modIRT

Examples

# the following code uses item parameter estimates previously obtained
# for examples that start from item response data see function modIRT

# three-parameter logistic model
# direct equating coefficients using the "Stocking-Lord" method
data(est3pl)
test <- paste("test", 1:5, sep = "")
mod3pl <- modIRT(coef = est3pl$coef, var = est3pl$var, names = test, display = FALSE)
direclist3pl <- alldirec(mods = mod3pl, method = "Stocking-Lord")
# compute chain equating coefficients for path 1,2,3,4
pth1 <- paste("test", 1:4, sep = "")
pth1 <- data.frame(t(pth1), stringsAsFactors = FALSE)
chainec1 <- chainec(direclist = direclist3pl, pths = pth1)
# compute chain equating coefficients for path 1,5,4
pth2 <- c(paste("test", c(1,5,4), sep = ""))
pth2 <- data.frame(t(pth2), stringsAsFactors = FALSE)
chainec2 <- chainec(direclist = direclist3pl, pths = pth2)
# compute chain equating coefficients for path 1,2,3,4,5
pth3 <- paste("test", 1:5, sep = "")
pth3 <- data.frame(t(pth3), stringsAsFactors = FALSE)
chainec3 <- chainec(direclist = direclist3pl, pths = pth3)
# create a list of objects of class eqc or ceqc
ecall <- c(chainec1, chainec2, chainec3, direclist3pl["test1.test5"])
# compute bisector and weighted bisector coefficients
allec <- bisectorec(ecall = ecall, weighted = TRUE, unweighted = TRUE)
summary(allec)

equateIRT documentation built on Oct. 4, 2024, 1:10 a.m.