The item information function (IIF) for the 3PL model can be computed as
iif(ip, items = NULL, x = NULL)
Item parameters: the output of est
, or a 3-column matrix
corresponding to its first element, est
.
The item(s) for which the information function is computed. If NULL (the default), irf for all items will be returned
The values of the latent variable (
A list of:
A copy of the argument x
A
matrix containing the IIF values: persons (values of (x
) as rows and
items as columns
A common use of this function would be to obtain a plot of the IIF.
# NOT RUN {
plot(iif(Scored2pl, items=1:3))
# }
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