Fits an Extended NOminal Response Model (ENORM) using conditional maximum likelihood (CML) or a Gibbs sampler for Bayesian estimation.
fit_enorm( dataSrc, predicate = NULL, fixed_params = NULL, method = c("CML", "Bayes"), nDraws = 1000, merge_within_persons = FALSE )
a connection to a dexter database, a matrix, or a data.frame with columns: person_id, item_id, item_score
An optional expression to subset data, if NULL all data is used
Optionally, a prms object from a previous analysis or a data.frame with parameters, see details.
If CML, the estimation method will be Conditional Maximum Likelihood; otherwise, a Gibbs sampler will be used to produce a sample from the posterior
Number of Gibbs samples when estimation method is Bayes.
whether to merge different booklets administered to the same person, enabling linking over persons as well as booklets.
An object of type
prms. The prms object can be cast to a data.frame of item parameters
using function `coef` or used directly as input for other Dexter functions.
To support some flexibility in fixing parameters, fixed_params can be a dexter prms object of a data.frame. If a data.frame, it should contain the columns item_id, item_score and a difficulty parameter. Three types of parameters are supported:
thresholds between subsequent item categories
Each type corresponds to a different parametrization of the model.
Maris, G., Bechger, T.M. and San-Martin, E. (2015) A Gibbs sampler for the (extended) marginal Rasch model. Psychometrika. 80(4), 859-879.
Koops, J. and Bechger, T.M. and Maris, G. (in press); Bayesian inference for multistage and other incomplete designs. In Research for Practical Issues and Solutions in Computerized Multistage Testing. Routledge, London.