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Subject |
RE: st: RE: FWD: poisson regression on aggrgregated data |

Date |
Mon, 9 Feb 2009 12:30:04 +0000 |

Dear Kieran No I am not modeling mortality rates, I am modeling the incident of experiencing an event by patients using these 2 covariates: Year_start (year of starting treatment): 1997,1998,1999,...,2008 time_since_start:0_1, 1_2, 2_3,...,Max My original data was not in aggregated form, and patients experienced the event (1) or not (0). Then I splitted the follow up time in one year periods and coded year_start,1997 as 1 and 1998+ as 2 and time_since start ,0_1 as 1, 1_2 as 2 and 2+ as 3. then aggregated data using these coded covariates: strate year_start_cat time_since_start_cat saved the output, and used poisson on _D (count of events in each group)-created by strate-, above 2 coded covariates (year_startcat, time_since_startcat) and the exposure that would be created aggregated follow up time _Y ,and then predicted number of events and incident rates in each group using predict. Now I would like to use the coefficients of this fitted poisson model and have the predicted incident rates in disaggregated data (for year_start and time_since_start before grouping them) for example the incident rate for year_start=2003 (whitch has been coded as year_startcat=2) and year_since_start=3_4 (which has been coded as year__since_startcat=3) Would it be correct if I use the same predicted incident rate from poisson on grouped data (1998+ and 2+) and use it for above example or each case in this group or in this case more events than really is will be predicted? Many thanks, Shell > Subject: st: RE: FWD: poisson regression on aggrgregated data > Date: Mon, 9 Feb 2009 04:09:31 +0900 > From: kamccaul@meddent.uwa.edu.au > To: statalist@hsphsun2.harvard.edu > > . > > It's not clear from this description what you are modelling. Is it > mortality rates? > Second, when you say that you have used aggregated data, is this data > that you have aggregated or was the data already in aggregated form? > > > > ______________________________________________ > Kieran McCaul MPH PhD > WA Centre for Health & Ageing (M573) > University of Western Australia > Level 6, Ainslie House > 48 Murray St > Perth 6000 > Phone: (08) 9224-2140 > Fax: (08) 9224 8009 > email: kamccaul@meddent.uwa.edu.au > http://myprofile.cos.com/mccaul > http://www.researcherid.com/rid/B-8751-2008 > ______________________________________________ > The fact that no one understands you doesn't make you an artist. > > -----Original Message----- > From: owner-statalist@hsphsun2.harvard.edu > [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Martin Weiss > Sent: Sunday, 8 February 2009 7:55 PM > To: statalist@hsphsun2.harvard.edu > Subject: st: FWD: poisson regression on aggrgregated data > > <> > > Dear [Redacted], > > short answer: I do not know! BTW, it is not clear to me why you want to > tap > only my wisdom when you can have the entire list. So I am forwarding > this > topic to the list for you... > > > HTH > Martin > _______________________ > > > Dear Martin > > I would like to ask the following question. > > I have used poisson regression on aggrgregated data with 2 covariates > (in a > cohort of HIV positive patients) > > 1.year of starting 3+ antiretroviral treatment (1997, 1998+) > 2.time since starting 3+antiretrovirals (0-1, 1-2, 2+) > > and I have predicted incident rates in this aggregated data using > predict > option after the poisson model. > > Now my question is if I want to have predicted incident rates for > patients > starting 3+ arvs at 2000 and time since starting 3+ arvs , 3_4 years > is it correct to use the same predicted incident rate obtained for > aggregated data and in this example use predicted incident rate for > 1998+ > and 2+? > > It would be greatly appreciated if you could answer my question, Please > let > me know if you would like me to provide more details. > > Thank you very much in advance, > > Kind regards, > Shell > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ > > > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ _________________________________________________________________ News, entertainment and everything you care about at Live.com. Get it now! http://www.live.com/getstarted.aspx * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**RE: st: RE: FWD: poisson regression on aggrgregated data***From:*"Kieran McCaul" <kamccaul@meddent.uwa.edu.au>

**References**:**st: FWD: poisson regression on aggrgregated data***From:*"Martin Weiss" <martin.weiss1@gmx.de>

**st: RE: FWD: poisson regression on aggrgregated data***From:*"Kieran McCaul" <kamccaul@meddent.uwa.edu.au>

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