Steve Simon wrote:
>
>There is one solution (TO LOW POWER), though it is unlikely to be adopted.
>When sample
>sizes are limited by the nature of the disease (childhood cancer is an
>example), then we should consider using a larger alpha level. Think in terms
>of new drugs. A Type I error is allowing an ineffective drug onto the marker
>and a Type II error is keeping an effective drug off the market. If the
>current statistical standard effectively prevents most effective drugs from
>getting to the market (high Type II error rate), then make it easier for ALL
>drugs to get onto the market by increasing the Type I error rate.
>
>I saw a presentation where someone ran a simulation model with certain
>assumptions about a limited study population and a certain rate of
>innovation. The simulation showed that under certain circumstances, an alpha
>level of 50% (!) was best. This rule allowed a lot of ineffective drugs onto
>the market, but these drugs were rapidly displaced by newer and better
>drugs. At 25% and 5% alpha levels, fewer ineffective drugs were allowed onto
>the market, but it also took longer for new innovations to be adopted.
>
>Perhaps the current standard of 5% alpha levels is stifling innovation. I
>don't see journals accepting 50% Type I error levels anytime soon, certainly
>not on the basis of a single simulation. But it is unclear why we disallow
>this practice while allowing Type II error levels of 60% or higher.
>
>Steve Simon, [log in to unmask], Standard Disclaimer.
>STATS - Steve's Attempt to Teach Statistics: http://www.cmh.edu/stats
As a researcher and a teacher of skills in reading the literature, I come
across the most determined resistance to consideration of modification of
the alpha level...even when there are no obvious adverse consequences to
falsely concluding that an effect is present. It is part of the fear of
statistics perhaps that this is, in so many 'academic' circles, strictly
non negotiable. The typical response I have to counter is
"You cannot move the goal posts"
Can you recommend a convincing discussion for those who refuse to enter a
debate on alpha level?
I would, while I am here, like to express my appreciation of Steve Simon's
input to this mailbase
cheers
jenny
__________________________________________________________________________
Jenny Keating PhD
MAPA, MMPA
Physiotherapist & Manipulative Physiotherapist
Lecturer PHONE: +61 3 9479 5815
School of Physiotherapy FAX: +61 3 9479 5768
Faculty of Health Sciences EMAIL: [log in to unmask]
La Trobe University
Bundoora Victoria 3083
AUSTRALIA
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