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# CITATION.cff file created with {cffr} R package
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cff-version: 1.2.0
message: 'To cite package "kits" in publications use:'
type: software
license: GPL-3.0-only
title: 'kits: Psychometric Tools for the Kids in Taiwan Developmental Scale'
version: 0.25.2
abstract: 'Tools for the developmental scale of KIT (Kids in Taiwan: National Longitudinal
  Study of Child Development and Care). Each model is written once and ''RTMB'' gives
  every derivative (the conditional maximum likelihood, the person scores, the threshold
  standard errors, the norms); the closed-form steps use base R, and the data are
  handled with ''dplyr'', ''tidyr'' and ''purrr''. Items are calibrated with the partial
  credit model (Masters, 1982) <https://doi.org/10.1007/BF02296272> by conditional
  maximum likelihood, written as the elementary symmetric functions of the step parameters.
  Cohorts are linked by mean/sigma (Marco, 1977) <https://doi.org/10.1111/j.1745-3984.1977.tb00033.x>
  on the Thurstonian thresholds, and anchor items link to the D score of the Global
  Scales for Early Development (Weber et al., 2019) <https://doi.org/10.1136/bmjgh-2019-001724>.
  Person scores are weighted likelihood estimates (Warm, 1989) <https://doi.org/10.1007/BF02294627>;
  for the partial credit model they equal the Jeffreys modal estimates (Firth, 1993)
  <https://doi.org/10.1093/biomet/80.1.27> (Magis, 2015) <https://doi.org/10.1007/s11336-013-9378-5>,
  which are computed by the Newton method of ''RTMB'', one per item set and raw score.
  Norms are continuous sinh-arcsinh norms (Jones and Pewsey, 2009) <https://doi.org/10.1093/biomet/asp053>
  fitted by maximum likelihood with the polynomial model and bounds of ''cNORM'' (Lenhard
  and Lenhard, 2021) <https://doi.org/10.1177/0013164420928457>, minimised by nlminb
  with the gradient and Hessian of ''RTMB''. Differential item functioning combines
  the likelihood-ratio test of Andersen (1973) <https://doi.org/10.1007/BF02291180>
  with the item-pair test of Bechger and Maris (2015) <https://doi.org/10.1007/s11336-014-9408-y>,
  computed by CML in each group. The linking error at each score and through a chain
  of links, the statistics of the waves as a vertical scale, the precision of each
  form across the scale, and IRT true-score and observed-score equating of raw scores
  follow Kolen and Brennan (2014) <https://doi.org/10.1007/978-1-4939-0317-7>. The
  plots are drawn with ''plotly''. The algorithms are also exported as plain functions
  (the ''algo_'' layer) that chain with the pipe, and kits_algorithm() names the steps,
  formulas and references behind a result; teaching scripts in ''inst/scripts'' recompute
  the estimates with ''RTMB'' on the demo data. The companion package ''kitsPreview''
  computes the same results with ''dexter'' and ''cNORM'' for validation.'
authors:
- family-names: Tsai
  given-names: Jie-Wen
  email: tsai.jiewen@gmail.com
preferred-citation:
  type: manual
  title: 'kits: Psychometric Tools for the Kids in Taiwan Developmental Scale'
  authors:
  - family-names: Tsai
    given-names: Jie-Wen
    email: tsai.jiewen@gmail.com
  year: '2026'
  notes: R package version 0.25.2
repository: https://jiewentsai.r-universe.dev
commit: 6df7a02b86825155a034e830f93d8623d20b0d5f
date-released: '2026-10-30'
contact:
- family-names: Tsai
  given-names: Jie-Wen
  email: tsai.jiewen@gmail.com