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
#> gs1lgc136 gs1lgc136
#>                                                                                                                                                                                    label
#> gs1lgc136 SF136 Can your child talk about things that will happen in the future using correct language (e.g., "Tomorrow he will attend school" or "Next week we will go to the market")?
#>             tau
#> gs1lgc136 74.65