simExam (version 1.0.0)

genTrueItems: Generate true item parameters for NEAT design

Description

Creates true item parameters for a 2-parameters IRT model for posterior generation of item responses, IRT implementation and equating. Compatible with the common-item, non-equivalent group design (see Kolen et. al. 2004).

Usage

genTrueItems(C, J, U, num.forms, min.a = 0.5, max.a = 2, mu.b = 0,
  sd.b = 1, anchor.type = "internal", output = "list",
  linkage.plan = NULL, ...)

Arguments

C

number of common items between two forms

J

number of items per form

U

number of unique items per form (only valid for external anchor)

num.forms

number of forms

min.a

Lower bound for the (uniform) distribution of item discrimination parameter

max.a

Upper bound for the (uniform) distribution of item discrimination parameter

mu.b

Mean of (normally-distributed) item difficulty parameter

sd.b

Standard deviation of (normally-distributed) item difficulty parameter

anchor.type

type of anchor item set ("internal" or "external")

output

type of output; "list" gives a list of used items per form, "matrix" gives a joint matrix (data.frame).

linkage.plan

matrix containing linkage plan

...

extra parameters to be passed to genItemBankInt() or genItemBankExt()

Value

List of true item parameters per form