# Re: st: comparing differences of rate differences

 From Ricardo Ovaldia To statalist@hsphsun2.harvard.edu Subject Re: st: comparing differences of rate differences Date Wed, 10 Mar 2004 05:05:06 -0800 (PST)

```Thank you Philip.

Best,
Ricardo.

> Depending on whether your "rates" are true incidence
> densities or
> cumulative rates (treated as proportions as your
> current analyses imply)
> you could use either the -ir- or -cs- commands of
> the epitab suite  (see
> -help epitab-). The  binary exposure variable is the
> year   and
> the   -by()-  option would have race as a 0/1
> variable as its
> argument.  The test for heterogeneity is a rather
> non-powerful test of
> whether the effect of year on admission differs
> between the races.
>
> Alternatively, model it (using -poisson- or -binreg-
> conception of the rate and the metric you wish to
> use) with a
> year*race  interaction term.
>
> eg for risk differences:
>
> binreg  admitted  year  race  year_X_race, rd
>
> The coefficient on the interaction term is of
> interest.
>
> Phil
>
>
>
>
> At 04:15 PM 9/03/2004 -0800, you wrote:
> >Dear all,
> >
> >This is not really a Stata question but I have been
> >unsuccessful finding a satisfactory answer. Any
> >assistance will be greatly appreciated.
> >
> >I have computed hospital admission rates for two
> >different years (1996, 2002). To compare these
> rates I
> >can simply use Stata’s ­prtest- (or ­tabulate- ) to
> >test whether these rates differ.
> >
> >Now, if I compute these rates separately for Whites
> >and Blacks, how can I test if the change in rates
> from
> >1996 to 2002 is different for whites than for
> blacks?
> >
> >Thank you,
> >Ricardo.
> >
> >
> >=====
> >Ricardo Ovaldia, MS
> >Statistician
> >Oklahoma City, OK
> >
> >__________________________________
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>
> Philip Ryan
> Associate Professor,
> Department of Public Health
> Associate Dean (Information Technology)
> Faculty of Health Sciences
> South Australia
> tel 61 8 8303 3570
> fax 61 8 8223 4075
> CRICOS Provider Number 00123M
>
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=====
Ricardo Ovaldia, MS
Statistician
Oklahoma City, OK

__________________________________
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*
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```