Do growth factors have "standard devi... PreviousNext
Mplus Discussion > Growth Modeling of Longitudinal Data >
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 Peggy Clements posted on Monday, October 22, 2007 - 1:07 pm
We are conducting a number of LGM in which we predict growth factors with other growth factors.

Specifically: two sets of latent growth factors (I & S) are estimated: one for income and one for children's internalizing symptoms.
The structural part of the model includes the following paths:
income_i --> internalizing_i
income_i --> internalizing_s
income_s --> internalizing_s

I want plot internalizing trajectories for children whose family income slope is higher than average, average, and lower than average. If I were conducting a path analysis using manifest predictor and outcome variables, I would to plot the trajectories for subjects with average income, -1 SD income, and +1 SD income.

However, income_s isn't a manifest variable, it's a latent variable, and so I don't have a standard deviation. Is there some analagous way to conceptualize higher than average, average, and lower than average income_s?

It has occurred to me that one possibility would be to calculate an estimated SD using the s.e. for income_s. But I don't know if this is appropriate? Is there another way that I should do this?

Thanks.
 Linda K. Muthen posted on Monday, October 22, 2007 - 3:01 pm
Growth factors are random. As such they have means and variances. Taking the square root of the variance gives the standard deviation.
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