Date: Tue, 1 Jul 2008 14:45:06 -0400
Reply-To: Sigurd Hermansen <HERMANS1@WESTAT.COM>
Sender: "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From: Sigurd Hermansen <HERMANS1@WESTAT.COM>
Subject: Re: Cedar Rapids, Iowa, How's the clean up going?
In-Reply-To: <4bc14e460807011044j3c32de25g2f99094c8049a24a@mail.gmail.com>
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Though I wouldn't presume to speak for all Bayesians and subjectivists,
I'd say that one would have to state what we know about the relation
between a 100 year flood and a 200 year flood. Specifically, how does an
instance of a 100 year flood 15 years ago affect the probability of a
200 year flood during the current year?
It seems likely that the concept of a x year flood really means that
over the next n*x years one should expect n floods of some magnitude. It
doesn't suggest anything about intervals between x year floods or
between x and 2*x floods. It also assumes that the future will follow
the same patterns as the past.
S
-----Original Message-----
From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of
ajay ohri
Sent: Tuesday, July 01, 2008 1:44 PM
To: SAS-L@LISTSERV.UGA.EDU
Subject: Re: Cedar Rapids, Iowa, How's the clean up going?
I wonder what are the odds of a 1 in 200 years event happening after 15
years of a 1 in 100 years event assuming the Bayes Theorem....Anyone
here who can help calculate the probabilty ?
On Tue, Jul 1, 2008 at 10:04 PM, Ed Heaton <EdHeaton@westat.com> wrote:
> Ben;
>
> It's interesting that the 1993 flood was considered a 100-year flood.
> (I was there, filling sandbags beside the River Des Peres.) Now, only
> 15 years later, we have a 200-year flood!
>
> Ed
>
> Ed Heaton
> TB-286
> #4818
>
>
>
> -----Original Message-----
> From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of
> ben.powell@CLA.CO.UK
> Sent: Monday, June 30, 2008 5:02 AM
> To: SAS-L@LISTSERV.UGA.EDU
> Subject: Re: Cedar Rapids, Iowa, How's the clean up going?
>
>
> On Fri, 27 Jun 2008 14:57:13 -0500, Paul A. Thompson
> <paul@WUBIOS.WUSTL.EDU> wrote:
>
> >I live in St Louis area. It is clear that the entire Mississippi
> >value
>
> >system is not working. There are levees everywhere, and they are
> >expensive to maintain. Yet, when the water rises, the levees have 3
> >effects, none of which are good:
> >
> >1) Exacerbate the overall effect of the rise. One geologist stated
> >that
> the
> >Mississippi used to have a 4 mile wide flood basin, and now the basin
> >is
> 1.5
> >miles wide. When you shrink that basin to that extent, you are gonna
> >see a rising river. Each levee built is a threat against all other
> >levees.
> Since
> >1993, levees have been raised. Now, many are failing.
> >
> >2) Cost more when they fail. In the St Louis area in 1993, an area
> >called the Chesterfield valley was under 10 ft water. Today, there
> >is the biggest strip mall in the area there, as well as 20000 houses.
> >These have been built in 15 years. If the levees fail, WHICH THEY
> >WILL
>
> >EVENTUALLY, the effects of levee "belief" + basic stupidity will make
> >the result a disaster of New Orleans magnitude. This area is unlikely
> >to be flooded this time, since the Mississippi is 10 ft lower at St
> >Louis than it was 15 years ago. However, I believe that eventually,
> >we will have a big flood again. And it will be a terrible thing.
> >
> >3) Cause people to behave like idiots. When you build a levee,
> >people act differently (see pt 2). Farmers believe that a field
> >behind a levee is not going to be flooded, and plant that field and
> >put expensive chemicals on
> it,
> >even when the waters are rising.
> >
> >Paul A. Thompson, Ph.D.
> >Division of Biostatistics, Washington University School of Medicine
> >660
>
> >S. Euclid, St. Louis, MO 63110-1093 314-747-3793
> >paul@wubios.wustl.edu
> >
>
> This is all true but the point is to make property insurable in the
> short term. This almost certainly does mean that the next flood will
> be worse, when it finally does happen, but if the engineering is sound
> and it doesn't arrive for 100 years then 1 such flood every 100 years
> is cheaper to insure than a smaller flood every 5 years.
>
> Rgds
>
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