Hi Folks,
I have a longitudinal dataset, which includes ~1800 total observations across 30 individuals. I am using xtmixed to understand whether the group means calculated across three time epochs are different (0- 11 years, 11-17y, 18y+). When I ran the below, to just compare times under 18y to above 18y I had no issues running predict to store fitted values (timedummy=1 for measures where the individual is over 18) and was able to produce lovely plots including both the fixed and random components.
xtmixed measure i.timedummy || record_id: i.timedummy, covarance(unstructured)
but when I switch to the below factor with three levels (stage = 0 in childhood, 1 for teenage years, 2 in adulthood) I can use predict to store the fixed effects but not the random effects. I get the perplexing error "BLUP calculation failed; estimation data have changed".
I have tried varying the covariance structure but this did not help.
I am sure I am overlooking something obvious... Any advice received with thanks.
Taya
I have a longitudinal dataset, which includes ~1800 total observations across 30 individuals. I am using xtmixed to understand whether the group means calculated across three time epochs are different (0- 11 years, 11-17y, 18y+). When I ran the below, to just compare times under 18y to above 18y I had no issues running predict to store fitted values (timedummy=1 for measures where the individual is over 18) and was able to produce lovely plots including both the fixed and random components.
xtmixed measure i.timedummy || record_id: i.timedummy, covarance(unstructured)
but when I switch to the below factor with three levels (stage = 0 in childhood, 1 for teenage years, 2 in adulthood) I can use predict to store the fixed effects but not the random effects. I get the perplexing error "BLUP calculation failed; estimation data have changed".
I have tried varying the covariance structure but this did not help.
I am sure I am overlooking something obvious... Any advice received with thanks.
Taya
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