sirt (version 0.31-20)

testlet.yen.q3: $Q_3$ Statistic of Yen (1984) for Testlets

Description

This function calculates the average Q3 statistic (Yen, 1984) within and between testlets.

Usage

testlet.yen.q3(q3.res, testlet.matrix)

Arguments

q3.res

An object generated by yen.q3

testlet.matrix

A matrix with two columns. The first column contains names of the testlets and the second names of the items. See the examples for the definition of such matrices.

Value

• A list with following entries
• testlet.q3
  Data frame with average $Q_3$ statistics within testlets
• testlet.q3.korr
  Matrix of average $Q_3$ statistics within and between testlets

References

Yen, W. M. (1984). Effects of local item dependence on the fit and equating performance of the three-parameter logistic model. Applied Psychological Measurement, 8, 125-145.

See Also

For estimating all $Q_3$ statistics between item pairs use yen.q3.

Examples

#########
# use data.read as an example
data(data.read)

# estimate the Rasch model
mod <- rasch.mml2( data.read)
mod$item

# estmate WLEs
mod.wle <- wle.rasch( dat = data.read , b = mod$item$b )

# Yen's Q3 statistic
mod.q3 <- yen.q3( dat = data.read , theta = mod.wle$theta , b = mod$item$b )

# Yen's Q3 statistic with testlets
items <- colnames(data.read)
testlet.matrix <- cbind( substring(  items,1,1) , items )
mod.testletq3 <- testlet.yen.q3( q3.res=mod.q3,testlet.matrix=testlet.matrix)
mod.testletq3