Lavaan.survey output help: what am I looking at?

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H. Kberg

Jan 5, 2020, 12:43:53 PM1/5/20
to lavaan
Hi all,

Im new with mediation analysis. Currently Im trying to do a really simple one with weighted survey data, so Im using lavaan,survey.

I have one mediator.

What does this output exactly telling me?

Cheers

My code is:

#Define model
modellvm <- ' # direct effect
LVMass ~ c*METquantthird
# mediator
ATPIIImets ~ a*METquantthird
LVMass ~ b*ATPIIImets
# indirect effect (a*b)
ab := a*b
# total effect
total := c + (a*b)'

fitlvm <- lavaan(modellvm, data = finalNEOtrailMET, ordered=c("ATPIIImets"), auto.var = T, std.lv = T, meanstructure = T, int.ov.free = T)
fitlvm.surv <- lavaan.survey(lavaan.fit = fitlvm, survey.design=designweightsMET)
summary(fitlvm.surv)

with output:

lavaan 0.6-5 ended normally after 39 iterations

Estimator                                         ML
Optimization method                           NLMINB
Number of free parameters                          7

Number of observations                           916

Model Test User Model:
Standard      Robust
Test Statistic                                 0.000       0.000
Degrees of freedom                                 0           0

Parameter Estimates:

Information                                 Expected
Information saturated (h1) model          Structured
Standard errors                           Robust.sem

Regressions:
Estimate  Std.Err  z-value  P(>|z|)
LVMass ~
METqntthrd (c)    5.858    1.390    4.214    0.000
ATPIIImets ~
METqntthrd (a)   -0.059    0.020   -2.908    0.004
LVMass ~
ATPIIImets (b)   11.258    2.322    4.849    0.000

Intercepts:
Estimate  Std.Err  z-value  P(>|z|)
.LVMass           85.395    3.089   27.646    0.000
.ATPIIImets        0.352    0.044    8.053    0.000

Variances:
Estimate  Std.Err  z-value  P(>|z|)
.LVMass          633.419   40.489   15.644    0.000
.ATPIIImets        0.177    0.009   20.296    0.000

Defined Parameters:
Estimate  Std.Err  z-value  P(>|z|)
ab               -0.663    0.262   -2.532    0.011
total             5.196    1.406    3.697    0.000

H. Kberg

Jan 5, 2020, 12:50:21 PM1/5/20
to lavaan
Btw

METquantthird = exogenous ordinal variable with 3 levels (1,2,3)
LVMass  = continuous variable
ATPIIImets = endogenous dichotome variable

Op zondag 5 januari 2020 18:43:53 UTC+1 schreef H. Kberg:

Terrence Jorgensen

Jan 6, 2020, 5:27:16 PM1/6/20
to lavaan
METquantthird = exogenous ordinal variable with 3 levels (1,2,3)
LVMass  = continuous variable
ATPIIImets = endogenous dichotome variable

If you have a binary mediator, you can't use lavaan.survey.  Well, you "can" use it like you did, by pretending the mediator and predictor variables are continuous, but the survey package does not have the functionality needed to adequately account for the categorical nature of ordered/binary variables.

Terrence D. Jorgensen
Assistant Professor, Methods and Statistics
Research Institute for Child Development and Education, the University of Amsterdam