Applies the adaptive test algorithm to determine the next step: administer the next item or stop test and return D-score.

Usage

dcat(
  txt = "",
  instrument = "gs1",
  key = "gsed2510",
  population = NULL,
  p = 50,
  sem_rule = 1.726,
  session = "",
  format = "3.1",
  ...
)

Arguments

txt: A JSON string, URL, or file with BDS data in JSON format. Data should conform to the BDS JGZ 3.2.5 specification.
instrument: A character vector with 3-position codes of instruments that should match. The default is instrument = "gs1" for GSED SF; instrument = NULL allows for all instruments.
key: String. They key identifies 1) the difficulty estimates pertaining to a particular Rasch model, and 2) the prior mean and standard deviation of the prior distribution for calculating the D-score. The default key key = "gsed2510".
population: String. Name of the reference population.
p: percentage to pass the item, difficulty in percentile units.
sem_rule: numeric target for sem can be estimated based on Cohen's d from sem_rule().
session: Optional session key if data is already uploaded to sitehost.
format: JSON schema version, e.g., "3.0". Used when uploading.
...: Ignored

Value

A string with an item name or a table.

Author

Iris Eekhout 2025

Examples

txt <- system.file("examples", "example_v3.1.json", package = "bdsreader")
dcat(txt = txt, p = 50)
#> [1] "gs1lgc110"