catSurv (version 1.6.0)

estimateThetas: Estimates of Ability Parameters for a Dataset of Response Profiles

Description

Estimates the expected value of the ability parameter \(\theta\), conditioned on the observed answers, prior, and the item parameters for complete response profiles for a dataset of respondents.

Usage

# S4 method for Cat
estimateThetas(catObj, responses)

Value

The function estimateThetas returns a vector containing respondents' estimated ability parameters.

Arguments

catObj

An object of class Cat

responses

A dataframe of complete response profiles

Author

Haley Acevedo, Ryden Butler, Josh W. Cutler, Matt Malis, Jacob M. Montgomery, Tom Wilkinson, Erin Rossiter, Min Hee Seo, Alex Weil

Details

Estimation approach is specified in estimation slot of Cat object.

The expected a posteriori approach is used when estimation slot is "EAP". This method involves integration. See Note for more information.

The modal a posteriori approach is used when estimation slot is "MAP". This method is only available using the normal prior distribution.

The maximum likelihood approach is used when estimation slot is "MLE". When the likelihood is undefined, the MAP or EAP method will be used, determined by what is specified in the estimationDefault slot in Cat object.

The weighted maximum likelihood approach is used when estimation slot is "WLE". Estimating \(\theta\) requires root finding with the ``Brent'' method in the GNU Scientific Library (GSL) with initial search interval of [-5,5].

See Also

Cat-class, estimateTheta

Examples

## Loading ltm Cat object
data(ltm_cat)

## Set different estimation procedures and estimate ability parameter
data(npi)
setEstimation(ltm_cat) <- "EAP"
estimateThetas(ltm_cat, responses = npi[1:25, ])