Date:         Wed, 26 Mar 2008 10:49:58 -0700
Reply-To:     "Dennis G. Fisher, Ph.D." <dfisher@CSULB.EDU>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "Dennis G. Fisher, Ph.D." <dfisher@CSULB.EDU>
Subject:      Re: 95% Confidence Interval for rate=0
Comments: To: Sarah Cox <saslearner2006@GMAIL.COM>
In-Reply-To:  <fd5d33210803261033q7a0c8ac1of60cf6c7be9869a8@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

What I use for these kinds of situations is a SAS macro written by
Leslie Daly that gives either binomial or
exact confidence intervals around a proportion.  I am not sure about the
0 percent.  I do not know how
that would change things. Is your infection rate a prevalence or an
incidence?  The newer versions of
PROC FREQ does some of these things now.
Dennis Fisher

Sarah Cox wrote:
> HI,
>
> We are doing a decease trasfusion transmission study and found for total 34
> patients, no one is infeced. So the infection rate is 0. Right now, I need
> to calcluate the 95% CIs for the infection rate. Can any expert let me know
> how to calculate it because it is not a normal distribution? Your advice is
> really appreciated!
>
> Sarah
>
>

--
Dennis G. Fisher, Ph.D.
Professor and Director
Center for Behavioral Research and Services
1090 Atlantic Avenue
Long Beach, CA 90813
Ph: 562-495-2330 x121
Fax: 562-983-1421