modsem (version 1.0.11)

relcorr_single_item: Reliability‑Corrected Single‑Item SEM

Description

Replace (some of) the first‑order latent variables in a lavaan measurement model by single composite indicators whose error variances are fixed from Cronbach's \(\alpha\). The function returns a modified lavaan model syntax together with an augmented data set that contains the newly created composite variables, so that you can fit the full SEM in a single step.

Usage

relcorr_single_item(
  syntax,
  data,
  choose = NULL,
  scale.corrected = TRUE,
  warn.lav = TRUE
)

Value

An object of S3 class modsem_relcorr (a named list) with elements:

syntax

Modified lavaan syntax string.

data

Data frame with additional composite indicator columns.

parTable

Parameter table corresponding to `syntax`.

reliability

Named numeric vector of reliabilities (one per latent variable).

AVE

Named numeric vector with Average Variance Extracted values.

lVs

Character vector of latent variables that were corrected.

single.items

Character vector with names for the generated reliability corrected items

Arguments

syntax

A character string containing lavaan model syntax. Must at least include the measurement relations (=~).

data

A data.frame, tibble or object coercible to a data frame that holds the raw observed indicators.

choose

Optional. Character vector with the names of the latent variables you wish to replace by single indicators. Defaults to all first‑order latent variables in syntax.

scale.corrected

Should reliability-corrected items be scale-corrected? If TRUE reliability-corrected single items are corrected for differences in factor loadings between the items. Default is TRUE.

warn.lav

Should warnings from lavaan::cfa be displayed? If FALSE, they are suppressed.

Details

The resulting object can be fed directly into modsem or lavaan::sem by supplying syntax = $syntax and data = $data.

Examples

if (FALSE) {
tpb_uk <- "
# Outer Model (Based on Hagger et al., 2007)
 ATT =~ att3 + att2 + att1 + att4
 SN =~ sn4 + sn2 + sn3 + sn1
 PBC =~ pbc2 + pbc1 + pbc3 + pbc4
 INT =~ int2 + int1 + int3 + int4
 BEH =~ beh3 + beh2 + beh1 + beh4

# Inner Model (Based on Steinmetz et al., 2011)
 INT ~ ATT + SN + PBC
 BEH ~ INT + PBC
 BEH ~ INT:PBC
"

corrected <- relcorr_single_item(syntax = tpb_uk, data = TPB_UK)
print(corrected)

syntax <- corrected$syntax
data   <- corrected$data

est_dca <- modsem(syntax, data = data, method = "dblcent")
est_lms <- modsem(syntax, data = data, method="lms", nodes=32)
summary(est_lms)
}