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Model syntax for Growth Model, possib... |
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I am trying to model growth for 4 time points in Grades 6, 7, 8, and 11. The means seem basically linear, except that Grade 11 is lower than expected. I'm running into problems specifying a model. What would be the difference in interpretation between these two examples? Is either considered piecewise? Thanks in advance for any help or advice! Heather 1) MODEL: IW SW | M6@0 M7@1 M8@2 M11*; IW WITH SW; 2) MODEL: IW SW | M6@0 M7@1 M8@2 M11@5; [M11*]; IW WITH SW; |
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In 1), the mean and covariance structures are both influenced by the free time score at M11. It is easily interpreted in a growth model framework. In contrast, in 2) the mean and covariance structures deviate from that of a growth model. You could also consider 2) MODEL: IW SW | M6@0 M7@1 M8@2 M11@5; [M11*]; IW WITH SW; You can see how the different choices influence the residuals for the means and the residuals for the variance-covariance matrix. |
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Dr. Muthen, Thank you so much for your quick response. That helps a lot. I will probably go with #1 then, as it will be easier for me to interpret and explain the results. Just to clarify the second part of your message. When you said... You could also consider 2) MODEL: IW SW | M6@0 M7@1 M8@2 M11@5; [M11*]; IW WITH SW; ...was that model supposed to be slightly different than my #2? Or were you suggesting to compare how my #1 and #2 affect the residuals, etc.? Thanks again, Heather |
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Yes, compare how your #1 and #2 affect the residuals and fit. |
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