itemfit.ppar {eRm}R Documentation

Residuals, Personfit and Itemfit Statistics

Description

pmat computes the expected person-item matrix with corresponding probabilities. residuals computes the squared and standardized residuals based on the observed and the expected person-item matrix. Chi-square based itemfit and personfit statistics can be obtained by using itemfit and personfit.

Usage

## S3 method for class 'ppar':
pmat(object)
## S3 method for class 'ppar':
itemfit(object)
## S3 method for class 'ppar':
personfit(object)
## S3 method for class 'ppar':
residuals(object,...)
## S3 method for class 'ifit':
print(x, ...)
## S3 method for class 'pfit':
print(x, ...)
## S3 method for class 'resid':
print(x, ...)

Arguments

object Object of class ppar, derived from person.parameter.
x Object of class ifit, pfit, or resid.
... Further arguments passed to or from other methods. They are ignored in this function.

Details

Value

Function pmat:

pmat Matrix of theoretical probabilities
i.fit Itemfit
i.df Degrees of freedom for itemfit statistics
p.fit Personfit
p.df Degrees of freedom for personfit statistics
st.res Standardized residuals
sq.res Squared standardized residuals

Note

Author(s)

Patrick Mair, Reinhold Hatzinger

References

Smith Jr., E. V., and Smith, R. M. (2004). Introduction to Rasch Measurement. JAM press.

See Also

person.parameter

Examples


# Rasch model, estimation of item and person parameters
data(raschdat1)
res <- RM(raschdat1)
p.res <- person.parameter(res)

# Matrix with expected probabilities and corresponding residuals
pmat(p.res)
residuals(p.res)

#Itemfit
itemfit(p.res)

#Personfit
personfit(p.res)


[Package eRm version 0.9.1.1 Index]