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Calcite | Level 5

Hi All,


I am trying to pre-specify / get a better understanding of how to perform a multivariate (3 or 4 outcomes) longitudinal repeated measures analysis where outcomes are measured daily over many months


If I had just a few time points then my research has guided me towards a random coefficient models in PROC MIXED such as that specified in “Analyzing Multivariate Longitudinal Data Using SAS® “.


But I am struggling to find details of models to account for "continuous" time.  I have seen mention of modelling time as a continuous variable, or the use of a splined covariance structure.  Would someone mind pointing me in the direction of some appropriate literature in relation to these, or other suggested methodologies please.


Thank you.

Lapis Lazuli | Level 10

time is continuous in the random coefficients model that you mention. You might want to look at brown and prescott's book:


i'm pretty sure they cover SAS (ie give code examples) and discuss random coefficient models and building a polynomial model for nonlinear relationship with time. Although, im not sure if they discuss the multivariate case

Calcite | Level 5

Great thank you so much for your reply and guidance  ... I will be looking at the book right away :).  

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