personfit.stat: Person Fit Statistics for the Rasch Model
In sirt: Supplementary Item Response Theory Models

personfit.stat

R Documentation

Person Fit Statistics for the Rasch Model

Description

This function collects some person fit statistics for the Rasch model (Karabatsos, 2003; Meijer & Sijtsma, 2001).

Usage

personfit.stat(dat, abil, b)

Arguments

`dat`	An `N \times I` data frame of dichotomous item responses
`abil`	An ability estimate, e.g. the WLE
`b`	Estimated item difficulty

Value

A data frame with following columns (see Meijer & Sijtsma 2001 for a review of different person fit statistics):

`case`	Case index
`abil`	Ability estimate `abil`
`mean`	Person mean of correctly solved items
`caution`	Caution index
`depend`	Dependability index
`ECI1`	`ECI1`
`ECI2`	`ECI2`
`ECI3`	`ECI3`
`ECI4`	`ECI4`
`ECI5`	`ECI5`
`ECI6`	`ECI6`
`l0`	Fit statistic `l_0`
`lz`	Fit statistic `l_z`
`outfit`	Person outfit statistic
`infit`	Person infit statistic
`rpbis`	Point biserial correlation of item responses and item `p` values
`rpbis.itemdiff`	Point biserial correlation of item responses and item difficulties `b`
`U3`	Fit statistic `U_3`

References

Karabatsos, G. (2003). Comparing the aberrant response detection performance of thirty-six person-fit statistics. Applied Measurement in Education, 16, 277-298.

Meijer, R. R., & Sijtsma, K. (2001). Methodology review: Evaluating person fit. Applied Psychological Measurement, 25, 107-135.

Examples

#############################################################################
# EXAMPLE 1: Person fit Reading Data
#############################################################################

data(data.read)
dat <- data.read

# estimate Rasch model
mod <- sirt::rasch.mml2( dat )
# WLE
wle1 <- sirt::wle.rasch( dat,b=mod$item$b )$theta
b <- mod$item$b # item difficulty

# evaluate person fit
pf1 <- sirt::personfit.stat( dat=dat, abil=wle1, b=b)

## Not run: 
# dimensional analysis of person fit statistics
x0 <- stats::na.omit(pf1[, -c(1:3) ] )
stats::factanal( x=x0, factors=2, rotation="promax" )
  ## Loadings:
  ##                Factor1 Factor2
  ## caution         0.914
  ## depend          0.293   0.750
  ## ECI1            0.869   0.160
  ## ECI2            0.869   0.162
  ## ECI3            1.011
  ## ECI4            1.159  -0.269
  ## ECI5            1.012
  ## ECI6            0.879   0.130
  ## l0              0.409  -1.255
  ## lz             -0.504  -0.529
  ## outfit          0.297   0.702
  ## infit           0.362   0.695
  ## rpbis          -1.014
  ## rpbis.itemdiff  1.032
  ## U3              0.735   0.309
  ##
  ## Factor Correlations:
  ##         Factor1 Factor2
  ## Factor1   1.000  -0.727
  ## Factor2  -0.727   1.000
  ##

## End(Not run)

sirt documentation built on May 29, 2024, 8:43 a.m.