Posted by
Maguin, Eugene on
URL: http://spssx-discussion.165.s1.nabble.com/SPSS-Syntax-MIXED-Model-tp5713934p5730190.html
I'm trying to visualize your project from your syntax and this is what I get. Five farms, on each farm two groups of calves. Breed comes in somehow. Maybe connected to farm, maybe connected to group, maybe connected to both. Groups are treated differently. Calves are measured, let's say weighed, three times but not always on the same number of days since time=0, whatever that point means. Calves are somewhat different ages at time 0.
I'm curious: What is the total N.
What is the variance of the time effect and the covariance of the time*intercept effect?
Presumably this model is a step in the mixed model analysis of these data. What was the model that first yielded the warning? Did you get the message with this model?
MIXED Weight WITH Time
/FIXED = Time | SSTYPE(3)
/METHOD = REML
/PRINT = G SOLUTION TESTCOV
/RANDOM = INTERCEPT Time | SUBJECT(ID) COVTYPE(UN).
Gene Maguin
-----Original Message-----
From: SPSSX(r) Discussion [mailto:
[hidden email]] On Behalf Of Steph Bullen
Sent: Monday, July 20, 2015 5:38 AM
To:
[hidden email]
Subject: Re: SPSS Syntax MIXED Model
Hi Ryan,
Thank you very much for your wonderful inputs - I hope you are still active on this list!
Some years on from that post, I am battling with a very similar data set to Zalihe.
I have run the main effects model as per the syntax you recommended to Zalihe in this post and it works well. However, when I add the time*<predictor variables. interactions it is giving me the following warning message:
"Iteration was terminated but convergence has not been achieved. The MIXED procedure continues despite this warning. Subsequent results produced are based on the last iteration. Validity of the model fit is uncertain."
My syntax is follows:
MIXED Weight BY Farm Group Breed WITH Age Time Baseline_Weight
/FIXED =Farm Breed Group Age Time Baseline_Weight Farm*Time Breed*Time Group*Time | SSTYPE(3)
/METHOD = REML
/PRINT = G SOLUTION TESTCOV
/RANDOM = INTERCEPT Time | SUBJECT(ID) COVTYPE(UN).
I am using SPSS 21.
My data set involves calves (ID) subjected to one of two treatments (Group) and weighed on Day 0 (Baseline_Weight), Day 42 (approx; actual days are identified under "Time) and Day 84. Breed, farm, age (at Day 0) are recorded.
Any assistance would be extremely gratefully received. You have no idea how helpful your inputs have been up until now. :)
Thank you in advance!
Steph
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