Title:	Develop Concise but Comprehensive Shortened Versions of Psychometric Instruments
Version:	1.0.2
Description:	Operationalizes the identification problem of which subset of items should be kept in the shortened version of a said psychometric instrument to best represent the set of items comprised in the original version of the said psychometric instrument.
Depends:	R (≥ 4.1.0)
Imports:	stats, utils
URL:	https://doi.org/10.32614/CRAN.package.shortr
License:	GPL (≥ 3)
Encoding:	UTF-8
Language:	en-US
RoxygenNote:	7.3.3
NeedsCompilation:	no
Packaged:	2026-04-14 10:00:44 UTC; loisfournier
Author:	Loïs Fournier [aut, cre], Alexandre Heeren [aut], Stéphanie Baggio [aut], Luke Clark [aut], Antonio Verdejo-García [aut], José C. Perales [aut], Joël Billieux [aut]
Maintainer:	Loïs Fournier <lois.fournier@unil.ch>
Repository:	CRAN
Date/Publication:	2026-04-14 13:20:02 UTC

Develop Concise but Comprehensive Shortened Versions of Psychometric Instruments

Description

Operationalizes the identification problem of which subset of items should be kept in the shortened version of a said psychometric instrument to best represent the set of items comprised in the original version of the said psychometric instrument.

Usage

shortr(
  n.mat,
  k,
  algorithm = base::c("brute.force", "simulated.annealing"),
  start.temp = 1,
  cool.fact = 0.999,
  stop.temp = 0.001,
  n.runs = 1000,
  seed = 5107,
  verbose = TRUE
)

Arguments

Details

Let N denote the indices corresponding to the set of items comprised in the original version of a said psychometric instrument, and let n = |N| denote its cardinality, with n \in \mathbb{N}. Let i, j \in N denote arbitrary indices. Let K \subset N denote the indices corresponding to the subset of items to be comprised in the shortened version of the said psychometric instrument, and let k = |K| denote its cardinality, with k \in \{1, \ldots, n-1\}. Let A = (a_{ij}) \in \mathbb{R}^{n \times n} denote a symmetric matrix of associations (e.g., of zero-order polychoric correlation coefficients) computed from the set of items comprised in the original version of the said psychometric instrument, satisfying A = A^\top \Leftrightarrow a_{ij} = a_{ji} for all i, j \in N. Each element a_{ij} represents an association (e.g., a zero-order polychoric correlation coefficient) between the items indexed by i and j. Let K^c = N \setminus K denote the complement of K in N, with |K^c| = n - k. The objective is to identify the subset of indices K \subset N of cardinality |K| = k that maximizes the sum of the absolute values of the associations a_{ij} for all i \in K and j \in K^c. Formally, such an identification problem is expressed as follows:

\max_{K \subset N, |K| = k} \sum_{i \in K} \sum_{j \in K^c} |a_{ij}|

Value

A list of two named objects pertaining to the solution to the identification problem yielded by the combinatorial search algorithm:

solution.character

A character denoting the subset of items to be comprised in the shortened version of the said psychometric instrument.

solution.numeric

A numeric denoting the sum of the absolute values of the associations between the subset of items to be comprised in the shortened version of the said psychometric instrument and the subset of items not to be comprised in the shortened version of the said psychometric instrument.

References

Fournier, L., Heeren, A., Baggio, S., Clark, L., Verdejo-García, A., Perales, J. C., & Billieux, J. (2026). shortr: Develop concise but comprehensive shortened versions of psychometric instruments (R package version 1.0.2) [Computer software]. doi:10.32614/CRAN.package.shortr

Examples

n.mat <- (
  stats::runif(n = 25^2, min = -1, max = 1) |>
  base::matrix(nrow = 25, ncol = 25) |>
  (\(m) (m + base::t(m)) / 2)() |>
  (\(m) {base::diag(m) <- 0; m})()
)

shortr::shortr(
  n.mat = n.mat,
  k = 5,
  algorithm = "brute.force"
)