write.anchor: Write anchor files for equating scales with common items.

In DJAnderson07/r2Winsteps: A package for interfacing between R and the Rasch modeling software Winsteps

Description

This function takes two primary argument: The raw dataframe of items to be analyzed, rawItmsDta, and an item file with item difficulties previously estimated, eqIfile. Note that the item identifiers in eqIfile must match the names of the items in rawItmsDta. The function will then write an anchor file with the common items specified as having a fixed item difficulty, according to their value in eqIfile.

Usage

write.anchor(rawItmsDta, eqIfile, anchorFileName = "AnchorFile",
  eqIDcol = ncol(eqIfile), eqDiffcol = "Difficulty")

Arguments

rawItmsDta	Raw dataframe of items to be analyzed. Must not contain any non-item response columns. The names of the items must match the item identifier in the item file (second argument in the function).
eqIfile	An item file (ifile) from a previously run model, which includes common items with the raw data file. The raw data file items will be estimated relative to the estimated item difficulties of these common items.
anchorFileName	Name of the anchor file to be written. Defaults to "AnchorFile".
eqIDcol	The column name or number in the item file that includes item identifiers. Defaults to the final column.
eqDiffcol	The column that item difficulties reside in the item file. Defaults to "Difficulty", which is the name of the column if r2Winsteps() was run to produce the ifile.

Value

Item anchor file for equating scales with common items.

DJAnderson07/r2Winsteps documentation built on Sept. 12, 2019, 1:06 a.m.