ltm: residuals – R documentation

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ltm

residuals

Residuals for IRT models

Description

Computes the residuals for vectors of response patterns.

Usage

## S3 method for class 'gpcm'
residuals(object, resp.patterns = NULL, order = TRUE, ...)

## S3 method for class 'grm'
residuals(object, resp.patterns = NULL, order = TRUE, ...)

## S3 method for class 'ltm'
residuals(object, resp.patterns = NULL, order = TRUE, ...)

## S3 method for class 'rasch'
residuals(object, resp.patterns = NULL, order = TRUE, ...)

## S3 method for class 'tpm'
residuals(object, resp.patterns = NULL, order = TRUE, ...)

Arguments

`object`	an object inheriting either from class `gpcm`, class `grm`, class `ltm`, class `rasch` or class `tpm`.
`resp.patterns`	a `matrix` or a `data.frame` of response patterns with columns denoting the items; if `NULL` the expected frequencies are computed for the observed response patterns.
`order`	logical; if `TRUE` the response patterns are sorted according to the residual estimates.
`...`	additional arguments; currently none is used.

Details

The following residuals are computed:

(O_i - E_i) / E_i^(1/2),

where O_i and E_i denote the observed and expected frequencies for the ith response pattern.

Value

A numeric matrix containing the observed and expected frequencies as well as the residual value for each response pattern.

Author(s)

Dimitris Rizopoulos d.rizopoulos@erasmusmc.nl

Examples

fit <- ltm(LSAT ~ z1)
residuals(fit)
residuals(fit, order = FALSE)

ltm

Latent Trait Models under IRT

v1.1-1

GPL (>= 2)

Authors

Dimitris Rizopoulos <d.rizopoulos@erasmusmc.nl>

Initial release

2018-04-17