mixRasch (version 1.1)

getItemDetails: Convenience function returning information about an individual item.

Description

This function extracts information about an individual item estimated using the mixRasch procedure.

Usage

getItemDetails(raschResult, item, class=1, camelCase=TRUE)

Arguments

raschResult

The result of a mixRasch analysis.

item

Either an integer representing the item position within the analysis or the item name (the column name from the dataframe used in the mixRasch analysis).

class

The class in a mixture Rasch analysis for which you want the item stats. In a standard Rasch analysis, class will always be 1.

camelCase

If TRUE, the variables returned are renamed to conform to camelCase style naming conventions.

Value

item.name

The name of the item.

n.cat

The number categories (e.g., 2 for dichotomous).

delta.i

Average step difficulty.

SE.delta.i

Standard error for delta.i.

tau

Step difficulty as a deviation from delta.i.

SE.tau

Standard error for tau.

infit

The infit statistic for the item

in.Z

The standardized infit statistic for the item

outfit

The outfit statistic for the item

out.Z

The standardized outfit statistic for the item

itemMean

The item mean, based on modal class.

pBis

The item-theta correlation, based on modal class.

bis

The item-theta polyserial correlation, based on modal class.

Details

The function only requires a mixRasch result and an item number or name. If the analysis is a mixture analysis, the class from which the result is to be taken must be provided. The camelCase option is available so results can be exported to other software that might not supprt some types of R names (e.g., names with "."s in them).

Examples

# Example data included with mixRasch
data(SimMix)

test1 <- mixRasch(SimMix,1,50, conv.crit=.0001, n.c=1)
getItemDetails(test1,2)