grp {irtoys}R Documentation

Bin the latent variable estimates

Description

Groups a vector of estimates of the latent variable into a histogram-like object. Typically invoked by function itf, unless the user wishes to access some of the non-default settings.

Usage

grp(theta, bin.type = "quant", bin.numb = 10, ref.type = "meds")

Arguments

theta The latent variable estimates to be binned
bin.type One of "autom", "gauss", or "quant". "autom" uses the algorithm of hist(), producing bins with highly variable frequencies. "gauss" and "quant" try to produce groups of roughly equal size. "gauss" assumes a Normal distribution while "quant" is based on the empirical quantiles. Default is "quant"
bin.numb The number of bins (only a suggestion when bin.type="autom")
ref.type The points at which itf will evaluate the IRF. One of "mids" (the mid-point of each bin), "meds" (the median of the values in the bin), or "means" (the mean of the values in the bin). Default is "meds". When "bin.type=autom", "meds" defaults to "mids"

Value

A list of:

breaks The breaks between adjacent bins
counts The number of values in each bin
ref Depending on ref.type, the mids of the bin, or the mean or median of the values in the bin

Author(s)

Ivailo Partchev

See Also

itf

Examples

data(Scored)
p.2pl  <- est(Scored, model="2PL", engine="ltm")
th.mle <- mlebme(resp=Scored, ip=p.2pl)
gr     <- grp(th.mle, bin.numb=7)

[Package irtoys version 0.1.1 Index]