sam  R Documentation 
Fit a Structural Equation Model (SEM) using the Structural After Measurement (SAM) approach.
sam(model = NULL, data = NULL, cmd = "sem", se = "twostep",
mm.list = NULL, mm.args = list(bounds = "wide.zerovar"),
struc.args = list(estimator = "ML"),
sam.method = "local", ...,
local.options = list(M.method = "ML", lambda.correction = TRUE,
alpha.correction = 0L, twolevel.method = "h1"),
global.options = list(), output = "lavaan")
model 
A description of the userspecified model. Typically, the model
is described using the lavaan model syntax. See

data 
A data frame containing the observed variables used in the model. 
cmd 
Character. Which command is used to run the sem models. The possible
choices are 
se 
Character. The type of standard errors that are used in the
final (structural) model. If 
mm.list 
List. Define the measurement blocks. Each element of the list should be either a single name of a latent variable, or a vector of latent variable names. If omitted, a separate measurement block is used for each latent variable. 
mm.args 
List. Optional arguments for the fitting
function(s) of the measurement block(s) only. See 
struc.args 
List. Optional arguments for the fitting function of the
structural part only. See 
sam.method 
Character. Can be set to 
... 
Many more additional options can be defined, using 'name = value'.
See 
local.options 
List. Options specific for local SAM method (these
options may change over time). If 
global.options 
List. Options specific for global SAM method (not used for now). 
output 
Character. If 
The sam
function tries to automate the SAM approach, by first
estimating the measurement part of the model,
and then the structural part of the model. See reference for more
details.
Note that in the current implementation, all indicators of latent variables have to be observed. This implies: no support for secondorder factor structures (for now).
If output = "lavaan"
, an object of class
lavaan
, for which several methods
are available, including a summary
method. If output = "list"
,
a list.
Rosseel and Loh (2021). A structuralaftermeasurement approach to Structural Equation Modeling. Psychological Methods. Advance online publication. https://dx.doi.org/10.1037/met0000503
lavaan
## The industrialization and Political Democracy Example
## Bollen (1989), page 332
model < '
# latent variable definitions
ind60 =~ x1 + x2 + x3
dem60 =~ y1 + a*y2 + b*y3 + c*y4
dem65 =~ y5 + a*y6 + b*y7 + c*y8
# regressions
dem60 ~ ind60
dem65 ~ ind60 + dem60
# residual correlations
y1 ~~ y5
y2 ~~ y4 + y6
y3 ~~ y7
y4 ~~ y8
y6 ~~ y8
'
fit.sam < sam(model, data = PoliticalDemocracy,
mm.list = list(ind = "ind60", dem = c("dem60", "dem65")))
summary(fit.sam)
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