conquestr (version 0.9.96)

makeItemList: makeItemList

Description

creates a list of matrices. Each matrix represent item parameters of the structure used in `simplef` (a matrix of k categories by three (category score, delta dot, tau)).

Usage

makeItemList(deltaDot, tau, scores = NULL)

Value

a list.

Arguments

deltaDot

a data frame or matrix of delta dots. If a data frame, column labels should be: "id", "itemid", "delta". "itemid" should be populated with an item label or be missing for all values. If a matrix, column order should be: "id", a unique item ID for each row; "itemid", item labels for each item (or NA); "delta", a delta dot.

tau

a data frame or matrix of taus for polytomous items. Only polytomous items should be in this file. If an item ID in `deltaDot` in not in `tau` it is assumed that the item is dichotomous. Where a polytomous item has k categories, there should be k-2 rows for that item in `tau`. For example, a 3-category item has categories k_1, k_2, and k_3. There will be one value in `tau` for this item. The tau parameters represent the deviation from the delta dot to give the item parameters for adjacent category boundaries (e.g., k_1 and k_2, and k_2 and k_3). The value in `tau` represents the the first category boundary (e.g., k_1 and k_2). The second category boundary is constrained to be the negative sum of the other values of tau for that item. If a data frame, column labels should be "id", "itemid", "step", "tau". If a matrix, the column order should be: "id", a unique item ID for each item matched with values in `deltaDot`; "itemid", item labels for each item (or NA); "step", an indicator of which step/item category this threshold represents (minimum value should be 1 and maximum value should be k-1); "tau" the value for the tau parameter associated with this step.

scores

a data frame of item response category scores. Not currently used - items are assumed to be scored as per the values in `tau$step`.

Examples

nItems<- 10
myItemsDeltaDot<- data.frame(
  id= seq(nItems),
  itemId= NA,
  delta = runif(nItems, -4, 1) # nItems items in range -4,1
)
myItemsTau<- data.frame(
  id = NA,
  itemId = NA,
  step = NA,
  tau = NA # this is only needed because the function is...in progress
)
myAbilities<- rnorm(100, 1, 2) # 100 person, offset from items - poor targeting (?)
myItemsList<- conquestr::makeItemList(deltaDot = myItemsDeltaDot, tau = myItemsTau)