grp {irtoys} | R Documentation |
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.
grp(theta, bin.type = "quant", bin.numb = 10, ref.type = "meds")
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" |
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 |
Ivailo Partchev
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)