# lavaan WARNING: some models are based on a different set of observed variables

86 views

### Leslie Rutkowski

Oct 3, 2018, 9:01:21 AM10/3/18
to lavaan
Hi all,

I'm putting together an unconditional vs. conditional growth curve model example and the two models - that only differ in terms of the time invariant covariates - produce the "different set of observed variables" error. But there is no missing data on the covariates. And I am dealing with nested models (unconditional is nested within conditional). Also, the sample sizes are the same between the two models. I can't figure out what might be generating this error. When I comment out the covariates, the model fit is identical.

Here is a replicable example:

library(lavaan)
library(reshape2)

#--------------------------
# Using Singer & Willett tolerance
# toward deviant behavior data
#--------------------------

# Wide data

#------------------------
# U-LGCM
ulgcm <- 'i =~ 1*tol11 + 1*tol12 + 1*tol13 + 1*tol14 + 1*tol15
s =~ 0*tol11 + 1*tol12 + 2*tol13 + 3*tol14 + 4*tol15
tol11 ~~ a*tol11
tol12 ~~ a*tol12
tol13 ~~ a*tol13
tol14 ~~ a*tol14
tol15 ~~ a*tol15
'
# Model fit and summary
ulgcm.fit <- growth(ulgcm, data = tolerance)
summary(ulgcm.fit)
#------------------------

#------------------------
# C-LGCM
clgcm <- '# The "growth" model
i =~ 1*tol11 + 1*tol12 + 1*tol13 + 1*tol14 + 1*tol15
s =~ 0*tol11 + 1*tol12 + 2*tol13 + 3*tol14 + 4*tol15
tol11 ~~ a*tol11
tol12 ~~ a*tol12
tol13 ~~ a*tol13
tol14 ~~ a*tol14
tol15 ~~ a*tol15
# Model to predict growth
i ~ male
s ~ male
i ~~ s
'

# Model fit and summary
clgcm.fit <- growth(clgcm, data = tolerance)
summary(clgcm.fit)

# Model comparison
lavTestLRT(ulgcm.fit, clgcm.fit)
#------------------------

### Yves Rosseel

Oct 7, 2018, 1:57:19 PM10/7/18
to make the models nested, you should add the covariates in the
unconditional model too, but fix the regression slopes to zero:

i ~ 0*male
s ~ 0*male

Yves.
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