Date:         Wed, 10 Aug 2005 06:11:15 -0700
Reply-To:     wei yi <wy78712@YAHOO.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         wei yi <wy78712@YAHOO.COM>
Subject:      how to combine two confidence intervals?
Content-Type: text/plain; charset=iso-8859-1

Hello, All
I have two samples, one for doctors and one for
hospitals. I have got the confidence intervals for the
estimators in doctors and hospitals.
For example, doctors total payment CI is
(120,000,000,  140,000,000) at alpha=.10 ;
hospitals total payment CI is
(150,000,000,  160,000,000) at alpha=0.10;
Then I want to get one interval for the total of
doctors and hospitals, how could I do that? Based on
the data, I used SRS for sampling the hospital, and I
used stratified sampling for doctors. I think direct
add up may not be correct, or the alpha need to be
changed.
Thank you for your help,
wei


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