Hi Koushik,
there is a way to add time points without recreating the base:
recon-all -long <tpNsubjid> <longbasesubjid> -addtp
-all
This is what the recon-all help says about that:
"If a new timepoint needs to be added to a longitudinal run where a
base subject
has already been created (from prior timepoints), then the -addtp
command
can be added to the -long command in order to 'fix-up' the
longitudinal
stream to accept the new timepoint. Note that the base subject is
*not*
recomputed using the new timepoint. This potentially introduces a
bias, and it
is recommended to NOT add a time point this way! Instead recreate
the base
from all time points and run all longitudinals again."
So it's up to you. But given you already have 5 time points in your
base and add only 1, you may be fine. The base should be pretty
stable with 5 and if the 6th is not too different, it should not
matter much. I don't think anyone has ever done a thorough analysis
about adding time points.
Best, Martin
On 03/11/2014 10:08 AM, Govindarajan,
Koushik Athreya wrote:
Dear FS experts,
I have a serial study in which I
have run cross-sectional and longitudinal analysis on 5 time
points. Now, I want to add a 6th time point to my
dataset. Do I have to rerun my base template creation step
from scratch or is there a way to just add further time points
to an existing template?
Thanks
Koushik
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Martin Reuter, Ph.D.
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Instructor in Neurology - Harvard Medical School
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