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RE: st: RE: Wald interval and the WSJ
I'm not clear about your simulations: This should be a binomial
distribution. I tried the binomialtail function as
binomialtal(100,5,.03) and got 0.182. If I use binomialtail(40,2,.03) I
get 0.338.
Tony
Peter A. Lachenbruch
Department of Public Health
Oregon State University
Corvallis, OR 97330
Phone: 541-737-3832
FAX: 541-737-4001
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of jverkuilen
Sent: Thursday, August 14, 2008 10:09 AM
To: [email protected]
Subject: RE: st: RE: Wald interval and the WSJ
"Lachenbruch, Peter wrote:
##5. I suspect most of us would regard two studies with p-values of
0.049
and 0.051 as showing about the same thing, so the worship of the p-value
is rather silly. A confidence interval would be better.##
There is an attachment showing the results of the various tests. They
range from 0.0484 for the Wald test to 0.0547 for the exact double
binomial test. The score test gave 0.0515. They didn't publish a
likelihood ratio test. My point is that all the tests gave similar
results. We shouldn't
worship p=0.05.###
In some sims I did---in the end to satisfy my own curiosity---I
simulated p-values by bootstrapping from a dataset that had an observed
p = .03. 40% exceeded '05....
JV
Peter A. Lachenbruch
Department of Public Health
Oregon State University
Corvallis, OR 97330
Phone: 541-737-3832
FAX: 541-737-4001
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Scott
Merryman
Sent: Thursday, August 14, 2008 5:18 AM
To: [email protected]
Subject: st: Wald interval and the WSJ
There is an interesting article in today's Wall Street Journal on the
use of the Wald interval in clinical trials.
"Boston Scientific Stent Study Flawed" by Keith Winstein, August 14,
2008; Page B1.
"But Boston Scientific's claim was based on a flawed statistical
equation that favored the Liberte stent, a Journal analysis has found.
Using a number of other methods of calculation -- including 14
available in off-the-shelf software programs -- the Liberte study
would have been a failure by the common standards of statistical
significance in research.
Boston Scientific isn't the only company to use the equation, known as
a Wald interval, which has long been criticized by statisticians for
exaggerating the certainty of research results. "
http://digg.com/business_finance/WSJ_com_Boston_Scientific_Stent_Study_F
lawed
Scott
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