umx: umxMI – R documentation

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umxMI

Report modifications which would improve fit.

Description

This function uses the mechanical modification-indices approach to detect single paths which, if added or dropped, would improve fit.

Usage

umxMI(
  model = NA,
  matrices = NA,
  full = TRUE,
  numInd = NA,
  typeToShow = "both",
  decreasing = TRUE
)

Arguments

`model`	An `mxModel()` for which to report modification indices
`matrices`	which matrices to test. The default (NA) will test A & S for RAM models
`full`	Change in fit allowing all parameters to move. If FALSE only the parameter under test can move.
`numInd`	How many modifications to report. Use -1 for all. Default (NA) will report all over 6.63 (p = .01)
`typeToShow`	Whether to shown additions or deletions (default = "both")
`decreasing`	How to sort (default = TRUE, decreasing)

Details

Notes:

Runs much faster with full = FALSE (but this does not allow the model to re-fit around the newly- freed parameter).
Compared to mxMI, this function returns top changes, and also suppresses the run message.
Finally, of course: see the requirements for (legitimate) post-hoc modeling in mxMI() You are almost certainly doing better science when testing competing models rather than modifying a model to fit.

References

https://github.com/tbates/umx

Examples

require(umx)
data(demoOneFactor)
manifests = names(demoOneFactor)
m1 = umxRAM("One Factor", data = demoOneFactor, type = "cov",
	umxPath("G", to = manifests),
	umxPath(var = manifests),
	umxPath(var = "G", fixedAt = 1)
)
# umxMI(m1, full=FALSE)

umx

Structural Equation Modeling and Twin Modeling in R

v4.10.10

GPL-3

Authors

Timothy C. Bates [aut, cre] (<https://orcid.org/0000-0002-1153-9007>), Gillespie Nathan [wit], Michael Zakharin [wit], Brenton Wiernik [ctb], Joshua N. Pritikin [ctb], Michael C. Neale [ctb], Hermine Maes [ctb]

Initial release

2021-11-30