Dear Svend,
thanks a lot for Your Kindness, Time and helping hints.
I beg Your pardon for my late thanking You, but I was unable to scan the
e-mails this afternoon.
Kind Regards,
Carlo
-----Messaggio originale-----
Da: [email protected]
[mailto:[email protected]] Per conto di Svend Juul
Inviato: mercoled� 30 maggio 2007 14.52
A: [email protected]
Oggetto: Re: st: inference on counts?
Carlo wrote:
I would like to compare with Stata 9/2SE two samples (SDO 2003 vs. SDO
2004)
of discharge diagnoses Diagnosis Related Groups (DRG)codes and check for
the
significance of the reduction occurred in inpatient hospitalizations
(RO)
during 2003 ( 835,158) - 2004 (775,287).
As these data seem counts, I supposed they have something to deal with
Poisson distribution, but I would kindly ask You all for some hints on
this
issue.
DRG codes RO - SDO 2003 RO -
SDO 2004
6 16,084 13,763
39 116,574 95,355
40 15,258 14,870
119 53,483 51,385
134 54,674 50,981
162 87,517 80,981
183 134,501 124,971
222 98,794 94,024
270 20,993 20,719
284 27,327 24,836
294 39,715 37,320
301 24,453 22,264
364 38,591 33,639
395 43,887 42,530
467 63,307 67,649
Total 835,158 775,287
--------------------------------------------------------
Provided the population at risk has the same size in 2003 and 2004
you may compare incidence rates, arbitrarily setting the time at
risk to 1 (or any other number you like, it does not matter).
-ir- (see [ST] epitab) estimates incidence rate ratios.
clear
input drg n0 n1
6 16084 13763
39 116574 95355
40 15258 14870
119 53483 51385
134 54674 50981
162 87517 80981
183 134501 124971
222 98794 94024
270 20993 20719
284 27327 24836
294 39715 37320
301 24453 22264
364 38591 33639
395 43887 42530
467 63307 67649
end
reshape long n , i(drg) j(year)
generate t=1
ir n year t , by(drg)
drg | IRR [95% Conf. Interval] M-H Weight
-----------------+-------------------------------------------------
6 | .8556951 .83638 .8754475 8042
(exact)
39 | .8179783 .8109994 .8250157 58287
(exact)
40 | .9745707 .9527422 .9968977 7629
(exact)
119 | .9607726 .949192 .9724938 26741.5
(exact)
134 | .9324542 .9212518 .9437915 27337
(exact)
162 | .9253174 .9165052 .9342134 43758.5
(exact)
183 | .9291455 .9220106 .9363351 67250.5
(exact)
222 | .9517177 .943247 .9602641 49397
(exact)
270 | .986948 .9681388 1.006122 10496.5
(exact)
284 | .9088447 .8933258 .9246301 13663.5
(exact)
294 | .9396953 .9264859 .9530916 19857.5
(exact)
301 | .9104813 .8940598 .9272009 12226.5
(exact)
364 | .8716799 .8590033 .8845404 19295.5
(exact)
395 | .9690797 .9562192 .9821125 21943.5
(exact)
467 | 1.068586 1.057052 1.080248 31653.5
(exact)
-----------------+-------------------------------------------------
Crude | .9283118 .9254456 .9311868
(exact)
M-H combined | .9283118 .9254467 .9311857
-------------------------------------------------------------------
Test of homogeneity (M-H) chi2(14) = 1779.56 Pr>chi2 = 0.0000
The IRR estimates are the incidence rate ratios (2004/2003).
Hope this helps
Svend
__________________________________________
Svend Juul
Institut for Folkesundhed, Afdeling for Epidemiologi
(Institute of Public Health, Department of Epidemiology)
Vennelyst Boulevard 6
DK-8000 Aarhus C, Denmark
Phone: +45 8942 6090
Home: +45 8693 7796
Email: [email protected]
__________________________________________
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