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Estimate PID-5 scale reliability

Source: R/reliability_pid5.R
reliability_pid5.Rd

Compute per-scale internal-consistency reliability — Cronbach's alpha and McDonald's omega — for the Personality Inventory for DSM-5: full version (PID-5, 220 items), short form (PID-5-SF, 100 items), or brief form (PID-5-BF, 25 items). Reliability is estimated on the reverse-keyed item responses, at the facet level for FULL/SF and the domain level for BF (the same scales score_pid5() outputs, before FULL/SF domain aggregation). The BF version also returns a Total row covering all 25 items; note that this scale spans five heterogeneous domains, so its internal consistency is not comparable to a domain's and is reported without further interpretation.

Usage

reliability_pid5(
  data,
  items,
  version = c("FULL", "SF", "BF"),
  srange = c(0, 3),
  alpha = TRUE,
  omega = TRUE
)

Arguments

data

A data frame containing (at least) all the PID items (numerically scored and in order).

items

A vector of column names (as strings) or numbers (as integers) corresponding to the PID items in order. Items must be supplied in instrument order; duplicated entries are an error.

version

A string indicating the version of the PID to score: "FULL", "SF", or "BF". Will be automatically capitalized. (default = "FULL")

srange

An optional numeric vector specifying the minimum and maximum values of the items, used for reverse-coding. (default = c(0, 3))

alpha

Optional logical; if TRUE, include a column of Cronbach's alpha per scale. (default = TRUE)

omega

Optional logical; if TRUE, include a column of McDonald's omega (total) per scale, estimated via a one-factor CFA (requires the lavaan package). (default = TRUE)

Value

A tibble with one row per scale and columns scale, nItems, and (when requested) alpha and omega.

Details

Alpha is computed by calc_alpha() (covariance-based, pairwise deletion) and omega by calc_omega() (one-factor lavaan CFA, FIML). A scale whose estimate cannot be computed (e.g. too few items or, for omega, a non-converging CFA or an uninstalled lavaan) is returned as NA rather than aborting the call.

Examples

# Facet-level reliability for the full PID-5 (alpha only)
reliability_pid5(sim_pid5, items = 1:220, version = "FULL", omega = FALSE)
#> # A tibble: 25 × 3
#>    scale                  nItems   alpha
#>    <chr>                   <int>   <dbl>
#>  1 Anhedonia                   8 -0.211 
#>  2 Suspiciousness              7 -0.211 
#>  3 Risk Taking                14 -0.0128
#>  4 Impulsivity                 6  0.141 
#>  5 Eccentricity               13  0.0554
#>  6 Distractibility             9 -0.154 
#>  7 Restricted Affectivity      7 -0.144 
#>  8 Submissiveness              4 -0.194 
#>  9 Withdrawal                 10 -0.0290
#> 10 Callousness                14  0.0147
#> # ℹ 15 more rows