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I have 12 data points (T1T12) and would like to model for potential cubic growth in GMM. I managed to fit a decent linear and quadratic growth models but am unclear on to determine the appropriate times in the syntax for a cubic model: i s  T1@0 T2@1 T3@2 T4@3.........T12@11 i s q  T1@0 T2@.01 T3@.04 T4@.09......T12@1.21 What would the appropriate syntax time be for a cubic model? i s q cub  T1@? T2@?..........T12? Thank you for your assistance. 


Yes, just add a fourth growth factor. 


Thanks for the quick response. Can you clarify exactly what you mean though. As shown in my initial post I already have four growth factors listed (i s q cub) before the "" symbol, but I am unclear on what I should list after the "@" symbol for each of the 12 time points. Thank you for your explanation. 


You list the linear time scores after the  symbol. I just noticed you did this incorrectly for the quadratic model. The time scores are always the linear and Mplus computes the others. Keep the on a small scale like 0 .1 .2 etc. 


Thank you for the clarification. It looks like I was making this more complicated than needed. I really appreciate your help. 

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