Calculates the start item from age for an adaptive test to measure D-score.

Usage

dcat_start(
  txt = "",
  instrument = "gs1",
  key = NULL,
  population = NULL,
  p = 50,
  session = "",
  format = "3.1",
  ...
)

Arguments

txt: A JSON string, URL or file
instrument: character vector with instrument names to use to select items
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 NULL sets key = "gsed2510". View dscore::builtin_keys for an overview of the available keys.
population: String. Name of the reference population
p: percentage to pass the item, difficulty in percentile units
session: Optional session key if data is already uploaded to sitehost.
format: String. JSON data schema version number. There are currently three schemas supported: "1.0", "1.1", "2.0", "3.0" and "3.1". Formats "1.0" and "1.1" are included for backward compatibility only. Use format = "3.1" for new applications.
...: Ignored

Value

A string of milestones.

Author

Iris Eekhout 2025

Examples

fn <- system.file("examples", "example_v3.1.json", package = "bdsreader")
dcat_start(txt = fn, p = 50)
#>                item
#> gs1moc134 gs1moc134
#>                                                                       label
#> gs1moc134 SF134 If you draw a circle can your child do it, just as you did?
#>             tau
#> gs1moc134 75.11