Search code examples
rfactor-analysisr-lavaan

Extracting Individual trajectories in Lavaan Growth Curve Models

I have successfully modeled longitudinal data from a study using the growth() function in the Lavaan package for R. I cannot find it documented anywhere on how to extract the predicted trajectories for each participant. I can only find the predicted trajectory for the group as a whole (given under the "Intercepts" portion of the summary output).

Solution

  • Use lavPredict

    model.syntax <- '
# intercept and slope with fixed coefficients
i =~ 1*t1 + 1*t2 + 1*t3 + 1*t4
s =~ 0*t1 + 1*t2 + 2*t3 + 3*t4

# regressions
i ~ x1 + x2
s ~ x1 + x2

# time-varying covariates
t1 ~ c1
t2 ~ c2
t3 ~ c3
t4 ~ c4
'

fit <- growth(model.syntax, data=Demo.growth)
summary(fit)

head(lavPredict(fit))

    Which will produce predicted estimates for each individual

                  i            s
[1,]  1.1378809  0.676301228
[2,] -2.5421940 -1.425974525
[3,] -0.1279434  0.966734762
[4,]  1.1682777  1.477200679
[5,] -0.5141435  0.006995809
[6,] -1.2646865  0.524024630