equat1pl: 1pl equating with optional elimination of linking DIF items

In weirichs/eatModel: Educational Assessment Tools for IRT Modeling using Conquest or TAM

1pl equating with optional elimination of linking DIF items

Description

Function does the 1pl linking according to equating.rasch from the sirt package. Moreover, optional elimination of items with linking DIF is allowed and linking error may be estimated via the jackknife method if testlets are specified.

Usage

equat1pl(results, prmNorm, item = NULL, domain = NULL, testlet = NULL, value = NULL, 
         excludeLinkingDif = TRUE, difBound = 1, iterativ = FALSE,
         method = c("Mean.Mean", "Haebara", "Stocking.Lord", "robust", "Haberman"), itemF = NULL,
         domainF = NULL, testletF = NULL, valueF = NULL, estimation=c("OLS", "BSQ", "HUB", "MED", "LTS", "L1", "L0"),
         b_trim=Inf, lts_prop=.5)

Arguments

results	The object returned by getResults. Alternatively, a data.frame with item parameters of the focus group. In this case, additional arguments (itemF, domainF, and valueF) have to be defined.
prmNorm	Data frame with normed anchor item parameters. Data frame must have at least two columns: items and item difficulties. Use the further arguments item, domain, testlet and value to define the column in which the corresponding parameter can be found. If item, domain, testlet and value is NULL, prmNorm must have only two columns: First column items, second column item difficulties. Column names then are irrelevant.
item	Optional: Give the number or name of the item identifier column in prmNorm.
domain	Optional: Give the number or name of the domain name in prmNorm. Only necessary if item identifiers are not unique in prmNorm (for example, if one item occurs several times, with a global item parameter and a domain-specific item parameter. Domain names in prmNorm must match dimension names in the object returned by getResults.
testlet	Optional: Give the number or name of the testlet name in prmNorm. Only necessary if linking errors should be estimated via the jackknife method.
value	Optional: Give the number or name of the parameter column in prmNorm.
excludeLinkingDif	Logical. Should items with linking DIF excluded?
difBound	Defines the boundary. Items with absolute linking DIF greater than the boundary will be removed from the linking procedure.
iterativ	Logical. Should the exclusion of linking DIF items executed in an iterative loop? (i.e. start with all items and compute linking constant, than remove the item with the most pronounced DIF and compute linking constant, and so on, until no item is left with |DIF|> difBound.
method	Linking method. If "Mean.Mean", "Haebara", or "Stocking.Lord", the function equating.rasch from the sirt package is called. If "robust", the function linking.robust from the sirt package is called. If "Haberman", the function linking.haberman from the sirt package is called.
itemF	Optional: Give the number or name of the item column in results.
domainF	Optional: Give the number or name of the domain column in results.
testletF	Optional: Give the number or name of the testlet column in teh results object. Only necessary if linking errors should be estimated via the jackknife method.
valueF	Optional: Give the number or name of the parameter column in results.
estimation	Applies only if method equals "Haberman". Estimation method. See the help page of linking.haberman from the sirt package for further details.
b_trim	Applies only if method equals "Haberman". Trimming parameter for item slopes. See the help page of linking.haberman from the sirt package for further details.
lts_prop	Applies only if method equals "Haberman". Proportion of retained observations in "LTS" regression estimation. See the help page of linking.haberman from the sirt package for further details.

Value

A list with equating information intended for further transformation by the transformToBista function.

Examples

# see example 5, 6, and 6a in the help file of defineModel()

weirichs/eatModel documentation built on Jan. 26, 2025, 4:01 p.m.