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Date:   Mon, 20 Feb 2012 19:54:21 +0000
Sender:   "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:   Chris Poole <drchrispoole@GMAIL.COM>
Subject:   Re: Insufficient memory for time-dependent Cox regression
Comments:   To: David Marso <>
In-Reply-To:   <>
Content-Type:   multipart/alternative;

Thanks for the prompt reply David,

I initially thought the same as you but didn't try such a big value for SET WORKSPACE.

There is a thread on IBM SPSS forum explaining how the number of computed values increases nearly exponentially using the TIME program. In our case, almost 20 billion are produced before the regression is computed.

We're also going to try running SPSS on a very large Amazon EC2 instance to improve performance.

Will let you know how we get on.



On Monday, 20 February 2012, David Marso <> wrote: > See if > SET WORKSPACE=some large number helps. > Default is 6144 (kbtes) . > > I thought most procedures just grabbed what is required but that may be a > false assumption. Hard to keep track of what does what etc... > I ran some *HUGE* MATRIX problems recently and my 4G machine happily > allowed SET WORKSPACE=200000 (ie 200M) and my 5000x5000 matrix inversion > test ran in about 30 minutes. > HTH, David > > > > Dr Chris Poole wrote >> >> Dear Listers, >> >> Does anyone have any advice about memory requirements for running >> time-dependent Cox regression analyses with large datasets. >> >> We have a dataset of 184,000 cases with a quarterly exposure variable >> observed for upto twenty years (therefore 80 time segments). >> >> In SPSS v.18 on recently purchased desktop PCs we keep getting >> 'Insufficient memory to process the command'. Annoying as this only seems >> to happen after the time program has run for many minutes. >> >> I appreciate some others' experiences of t/d Cox regression and any >> solutions they found to overcome memory problems. >> >> Kind regards, >> >> Chris. >> >> -- >> Dr Chris Poole >> Senior Lecturer in the Evaluation of Medicines >> Department of Primary Care & Public Health >> School of Medicine >> Cardiff University >> Cardiff MediCentre, Heath Park, Cardiff, CF14 4UJ >> +44 (0)29 2068 2102 >> > > > -- > View this message in context: > Sent from the SPSSX Discussion mailing list archive at > > ===================== > To manage your subscription to SPSSX-L, send a message to > LISTSERV@LISTSERV.UGA.EDU (not to SPSSX-L), with no body text except the > command. To leave the list, send the command > SIGNOFF SPSSX-L > For a list of commands to manage subscriptions, send the command > INFO REFCARD >

-- Chris Poole E: <> | P. +44(0)7733004258


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