FunctionOverview

ESEM Invariance Script Writter
=====================================

Overview
-----------------------------------
The esemInvaTarget function aims to take minimal user input and and return 13 fully functioning MPlus scripts for invariance across multiple groups. i.e., across gender or experimental conditions. Each script will fit one model of Marsh et al. typology of invariance models starting with a free or configural model with model 13 fitting a complete invariance model. From the configural model, subsequent models progressively holding elements of the model invariant between groups. The function should support invariance for two or more groups. The models are as follows:

- M1 – Configural
- M2 – FL
- M3 – FL, Uniq
- M4 – FL, FVCV
- M5 – FL, Inter
- M6 – FL, Uniq, FVCV
- M7 – FL, Uniq, Inter
- M8 – FL, FVCV, Inter
- M9 – FL, Uniq, FVCV, Inter
- M10 – FL, Inter, Latent Means
- M11 – FL, Uniq, Inter, Latent Means
- M12 – FL, FVCV, Inter, Latent Means
- M13 – FL, Uniq, FVCV, Inter, Latent Means

Key:
- FL = Item factor loadings
- Uniq = Item uniquenesses/residuals
- Inter = Item intercepts
- FVCV = Latent variable factor variance covariance matrix

What is NOT supported.
--------------------------
The scripts produced are for target rotation ONLY. Upcoming functions will provide support for other rotations. Target rotation is the most difficult to program hence we started with it.

The scripts also do not support longitudinal invariance but it is on the list of function to be developed.

What it does.
----------------------------
The function first checks input. Mplus has a number of restriction on input files and the extensive checks aim to ensure they are met. The only exception to this is for variable names. Mplus requires variable names to be 8 characters or less but will run input scripts with more characters by truncating the names. As such the input script should run, however, too many variables with over 8 characters may make a script run over line character limits and result in odd output. For this reason it is best to ensure all variables are 8 characters or less. The functions here will return a warning for variables over 8 characters but will not produce an error.

Example
--------------------------
Using Data from simulated model:

esemInvaTarget(2, data, GroupVar = "group", c("males", "females"), 1:12, FileOut="ESEM", FileIn="ESEM/ESEM.dat", Pattern=list(c(1,6), c(7,12)),LatentNames=c("Latent1", "Latent2"))

The entire work flow can be run passively by imputing the following code into R:

----------------------------------------------------------------------------
	trial<-"http://raw.github.com/pdparker/ESEM/master/exampleScript_ESEMS.R"
	source(url(trial))
----------------------------------------------------------------------------