Hi Karen,
To do multilevel/mixed effects modeling then yes, the files will need to be
in the "vertical" structure. However, I often find that I end up needing
both formats of the files - eg, vertical for the analysis, but horizontal
for some of the charts.
SPSS has the CASETOVARS command (Data> Restructure Wizard) for transforming
from one structure to the other.
Cheers,
Kylie.
-----Original Message-----
From: SPSSX(r) Discussion [mailto:
[hidden email]] On Behalf Of
Karen Harker
Sent: Monday, 16 February 2009 10:15 AM
To:
[hidden email]
Subject: Horizontal or vertical file structure for repeated measures
I have inherited a set of SPSS files for several ongoing clinical trials,
some of which involve numerous follow-up assessments. The files for each of
the assessments are in a horizontal file structure with separate sets of
variables for each of the follow-ups (i.e. dep01_f1 for follow-up 1,
dep01_f2 for follow-up #2, etc.). This has resulted in data sets that are
fairly shallow (<100 records) but quite wide (>3000 variables). Eventually,
the researcher will be wanting to do multilevel modeling, in addition to
time-series analysis.
I come from a database management background with only limited statistical
analysis experience. I'm uncomfortable with the horizontal file
structure...it goes against the grain of my RDBMS training. Furthermore,
I've read that SAS (and SPSS?) needs to have the data in vertical structure
for mixed-method analysis. Before I propose that the data be converted to
vertical file structure, I would like to know if there are other
considerations that make the horizontal structure better?
Thanks.
Karen R. Harker, MLS
UT Southwestern Medical Library
5323 Harry Hines Blvd.
Dallas, TX 75390-9049
214-648-8946
http://www.utsouthwestern.edu/library/=====================
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