nlsem (version 0.8-1)

lav2nlsem: Create a structural equation model from lavaan syntax

Description

Create model matrices from a string specifying a structural equation model in lavaan syntax.

Usage

lav2nlsem(model, constraints=c("indirect", "direct1", "direct2"),
            class.spec="class")

Value

Gives back an object of class singleClass, semm, or

nsemm which can be fitted using em.

Arguments

model

A description of the user-specified model. The model is described using the lavaan model syntax. See Details in ?model.syntax in lavaan for more information.

constraints

which should be set for a model with more than one latent class. See Details in ?specify_sem.

class.spec

String used to specify latent classes. Can be any string e.g. `class', `mixture', etc. Default is `class'.

Details

nlsem can only fit a certain group of models and it is only feasible to specify models in the lavaan syntax that can be fitted with nlsem; that means models with latent variables and latent interactions only.

Parameter restrictions in lavaan style can be used to some extent; meaning parameters can be fixed to a certain value with 1*x1. Equality restrictions are handled via the constraints argument and will be ignored in the lavaan syntax.

References

Rosseel, Y. (2012). lavaan: An R Package for Structural Equation Modeling. Journal of Statistical Software, 48(2), 1 - 36. doi:http://dx.doi.org/10.18637/jss.v048.i02

See Also

specify_sem, create_sem

Examples

# create model with three latent classes
lav.model <- '
          class: 1
          eta =~ y1 + y2 + y3 + y4
          xi1 =~ x1 + x2 + x3 + x4 + x5
          xi2 =~ x6 + x7 + x8 + x9 + x10 + x11

          eta ~ xi1 + xi2 + xi1:xi1

          class: 2
          eta =~ y1 + y2 + y3 + y4
          xi1 =~ x1 + x2 + x3 + x4 + x5
          xi2 =~ x6 + x7 + x8 + x9 + x10 + x11

          eta ~ xi1 + xi2 + xi1:xi2 + xi1:xi1

          class: 3
          eta =~ y1 + y2 + y3 + y4
          xi1 =~ x1 + x2 + x3 + x4 + x5
          xi2 =~ x6 + x7 + x8 + x9 + x10 + x11

          eta ~ xi1 + xi2 + xi1:xi2'

model <- lav2nlsem(lav.model, constraints = "direct1", class.spec = "class")