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Mplus Discussion > Growth Modeling of Longitudinal Data >
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 Robert Tilgi posted on Friday, June 01, 2012 - 12:21 am
Hey everyone,
At the moment I try to create a growth curve for anxiety over seven sequenced measure points. I would like to determine the slope factor as a linear function of the passed time. Besides the Intercept-parameter shall be explained through a few person-specific covariates (GE,SEB,ASK,FSSK,ERW,EXT,WI). Overall it shall become a multilevel analysis with longitudinal data.
Since now I have written the following command:

title: Computing the growth curve
data: file = DataforLWK.dat;
variable: names = PA1,PA2,PA3,PA4,PA5,PA6,PA7,GE,SEB,ASK,FSSK,ERW,EXT,WI;
missing = all (-99);
model: interc linear | PA1@0 PA2@1 PA3@2 PA4@3 PA5@4 PA6@5 PA7@6;
interc on GE,SEB,ASK,FSSK,ERW,EXT,WI;
output: sampstat standardized stdyx;
plot: type = plot3;
series = PA1 (linear) PA2 (linear) PA3 (linear)
PA4 (linear) PA5 (linear) PA6 (linear);

Is this command correct?

Rolph
 Robert Tilgi posted on Friday, June 01, 2012 - 12:21 am
Iím confused by one thing: When I run the command and display the graphic "Sample & estimated means", the estimated means show a horizontal curve. But I thought that I made clear that the curve should gain linearly ("interc linear | PA1@0 PA2@1 PA3@2 PA4@3 PA5@4 PA6@5 PA7@6"). Can someone help me with that?
Many thanks!
 Linda K. Muthen posted on Friday, June 01, 2012 - 9:56 am
What is the mean of linear? See TECH4 to find it.
 Robert Tilgi posted on Saturday, June 02, 2012 - 2:22 am
The estimated mean of linear is -0.003. What shall I do now?
 Linda K. Muthen posted on Saturday, June 02, 2012 - 8:44 am
This value is the average slope of the growth curve. It is zero or flat -- a horizontal line. Look at your observed means. They probably show this same trend.
 Robert Tilgi posted on Sunday, June 03, 2012 - 2:15 am
But my theory says that the values should rise linearly. Can't I estimate a model with, let's say, has a growth of 1 instead of zero?
 Linda K. Muthen posted on Sunday, June 03, 2012 - 6:30 am
Your data does not seem to agree with your theory. The results show what is found in the data.
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