ItemLoop {pleLMA}

loops through items and up-dates estimates of scale values for each item in Nominal Model

Description

This is a core function of the pseudo-likelihood algorithm for items of the nominal model. The function calls function 'ItemData' to create the data frame for input into 'mlogit', which is use to fit a conditional multinomial model (i.e., a discrete choice model) for each item. The up-dated scale are put into the Master data frame and added to the item.log array. Generally the function would not run outside of 'fit.nominal' or 'ple.lma'.

Usage

ItemLoop(
  Master,
  item.log,
  Phi.mat = Phi.mat,
  PersonByItem,
  npersons,
  nitems,
  ntraits,
  ncat,
  nless,
  TraitByTrait,
  pq.mat,
  LambdaName,
  NuName,
  fitem
)

Arguments

Master

Current master frame

item.log

Iteration history for the items parameters

Phi.mat

Current estimate of Phi.mat

PersonByItem

Person by item adjacency matrix (same as inData)

npersons

Number of persons

nitems

Number of items

ntraits

Number of traits

ncat

Number of categories

nless

Number of unique lambda and unique nus (ncat-1)

TraitByTrait

TraitsByTrait adjacency matrix (sam as TraitAdj)

pq.mat

One dimensional array for computing rest-scores

LambdaName

Marginal effect names used in formula and item data frame for item regressions

NuName

Scale values names in used in formula and item data frame for item regressions

fitem

Formula for item regression

Value

Master Master data frame up-dated scale values for all items

item.log Iteration history of item parameters where the last row showing results from the current iteration