Searches the item bank for matching items, and returns the difficulty estimates. Matching is done by item name. Comparisons are done in lower case.
get_tau(items, key = NULL, itembank = dscore::builtin_itembank)
A character vector containing names of items to be
included into the D-score calculation. Milestone scores are coded
1 (pass) and
0 (fail). By default,
D-score calculation is done on all items found in the data
that have a difficulty parameter under the specified
A string that selects a subset in the itembank that
makes up the key, the set of difficulty
estimates from a fitted Rasch model.
The built-in keys are:
"dutch". Since version 1.5.0, the
key = "gsed"
selects the latest key starting with the string "gsed".
key = "" to use all item names,
which should only be done if there are no duplicate itemnames
in the itembank.
data.frame with columns
label. Only columns
tau are required.
The function uses
A named vector with the difficulty estimate per item with
# difficulty levels in the GHAP lexicon get_tau(items = c("ddifmd001", "DDigmd052", "xyz")) #> ddifmd001 DDigmd052 xyz #> 8.61 NA NA