Date:         Wed, 19 Oct 2005 11:29:03 -0700
Reply-To:     Dale Glaser <glaserconsult@sbcglobal.net>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         Dale Glaser <glaserconsult@sbcglobal.net>
Subject:      Time Series inquiry.......
In-Reply-To:  <200510180708.j9I78nGP001491@listserv.cc.uga.edu>
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Hi all.....I will be working on a project whereby there are 99 matches (i.e., 198 participants in the study) with approximately one dozen variables measured on a varying basis over a varying number of days.  For example from one matched pair one individual from the experimental group is measured on one variable (e.g., respiratory rate) 8 times on day 1, then 9 times on day 2, and then 4 times on day 6; their matched cohort (control group) may be in the study for five days and have a very different number of measures per day.  Also, the time by which they were measured was not standardized (i.e., not all were measured at 8 am, 9 am, etc.).  There can be from 10 to 80 measures per person on a given variable given the length of their participation.  I was envisioning a multi-sample latent growth curve approach until I found out the # of measures (note: the client would indeed like to model ALL the measures as opposed to collapsing across time/days).  Subsequently, a time series approach
 was proposed (e.g., ARIMA) though I am having difficulty how to best pool the 198 particpants given the varying rates of measures across a varying rate of days.

If anyone has had experience with such a design, I would be most appreciative if you would be wiling to shed insight about the optimal way to handle such a time-unstructured design. I have pondered a mixed-model approach or pooled time series, but the number of measures across time see to prohibit a mixed-model approach (I do have HLM6.0 and Mplus) and I"m not sure if pooled time series is appropriate (i.e, does each column represent an individual's 10- 80 or so measures, and are they collapsed?).

Again, thank you for your time...Dale Glaser




Dale Glaser, Ph.D.
Principal--Glaser Consulting
Lecturer--SDSU/USD/AIU
4003 Goldfinch St, Suite G
San Diego, CA 92103
phone: 619-220-0602
fax: 619-220-0412
email: glaserconsult@sbcglobal.net
website: www.glaserconsult.com