The P value

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WiseOne
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The P value

Post by WiseOne » Tue Apr 03, 2018 7:20 am

A proposal to lower the P value threshold for significance from 0.05 to 0.005:

https://jamanetwork.com/journals/jama/f ... le/2676503

I can't wait to see how many studies that have been used to influence medical care would be instantly negated. I've long been dubious about the idea that every living human should undergo regular diagnostic testing and take multiple preventive medications without an individualized benefit/risk/cost assessment. It seems I'm not such a nut ball after all.
Multiple misinterpretations of P values exist, but the most common one is that they represent the “probability that the studied hypothesis is true.” A P value of .02 (2%) is wrongly considered to mean that the null hypothesis (eg, the drug is as effective as placebo) is 2% likely to be true and the alternative (eg, the drug is more effective than placebo) is 98% likely to be correct. Overtrust ensues when it is forgotten that “proper inference requires full reporting and transparency.” Better-looking (smaller) P values alone do not guarantee full reporting and transparency. In fact, smaller P values may hint to selective reporting and nontransparency. The most common misuse of the P value is to make “scientific conclusions and business or policy decisions” based on “whether a P value passes a specific threshold” even though “a P value, or statistical significance, does not measure the size of an effect or the importance of a result,” and “by itself, a P value does not provide a good measure of evidence.”

These 3 major problems mean that passing a statistical significance threshold (traditionally P = .05) is wrongly equated with a finding or an outcome (eg, an association or a treatment effect) being true, valid, and worth acting on. These misconceptions affect researchers, journals, readers, and users of research articles, and even media and the public who consume scientific information. Most claims supported with P values slightly below .05 are probably false (ie, the claimed associations and treatment effects do not exist). Even among those claims that are true, few are worth acting on in medicine and health care.

My emphasis. If only Machine Ghost were still around!
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Xan
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Re: The P value

Post by Xan » Tue Apr 03, 2018 9:00 am

WiseOne wrote:I've long been dubious about the idea that every living human should undergo regular diagnostic testing and take multiple preventive medications without an individualized benefit/risk/cost assessment. It seems I'm not such a nut ball after all.
WiseOne, what's your take on the flu vaccine in light of the above?
WiseOne
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Re: The P value

Post by WiseOne » Tue Apr 03, 2018 11:24 am

Oh boy...the trouble begins already...

In the case of measles where there's a "herd effect" ie a public health reason to maintain high levels of vaccination, to protect people who can't tolerate the vaccine, there is no question in my mind: everyone should get it if they can. (NB: this is another reason why millions of people in this country illegally are a problem, because unless you're willing to put them all on Medicaid and pay that much more in state and local taxes, it means that it's nearly impossible for herd immunity to be reliably present here.)

In the case of flu, you don't have that situation so it becomes a personal benefit/risk decision. At least one hospital I'm aware of IMHO has gone over the line with their requirement for even employees allergic to eggs to take the vaccine. On the other hand, you should know that healthy people in their 20s and 30s have died from this year's flu, while the elderly have had relatively mild symptoms. I'm personally glad I got the vaccine given this, even if all it does is shorten the course/reduce symptoms. The problem is you don't know in advance how the year will play out.
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Kriegsspiel
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Re: The P value

Post by Kriegsspiel » Wed Apr 25, 2018 7:07 am

WiseOne wrote: In the case of flu, you don't have that situation so it becomes a personal benefit/risk decision. At least one hospital I'm aware of IMHO has gone over the line with their requirement for even employees allergic to eggs to take the vaccine. On the other hand, you should know that healthy people in their 20s and 30s have died from this year's flu, while the elderly have had relatively mild symptoms. I'm personally glad I got the vaccine given this, even if all it does is shorten the course/reduce symptoms. The problem is you don't know in advance how the year will play out.
I got my first flu vaccine in a while after reading The Great Influenza by Barry, about the 1918 pandemic. I also read Parasite Rex last year, now I wash my hands a lot more. And stopped eating roadkill.
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Kriegsspiel
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Re: The P value

Post by Kriegsspiel » Wed Apr 25, 2018 11:46 am

O0
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Mountaineer
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Re: The P value

Post by Mountaineer » Wed Apr 25, 2018 12:54 pm

Kriegsspiel wrote:O0
Hey K, re roadkill, I think I remember where you are from. ;) The place where a 7 course meal is a roadkill possum and a six pack. ;D
DNA has its own language (code), and language requires intelligence. There is no known mechanism by which matter can give birth to information, let alone language. It is unreasonable to believe the world could have happened by chance.
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Kriegsspiel
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Re: The P value

Post by Kriegsspiel » Wed Apr 25, 2018 1:27 pm

I am now offended by the distinct anti-Appalachian bias here! rabble rabble
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Mountaineer
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Re: The P value

Post by Mountaineer » Wed Apr 25, 2018 3:26 pm

Kriegsspiel wrote:I am now offended by the distinct anti-Appalachian bias here! rabble rabble
Make that rebel rebel. Are you not from south of the Mason-Dixon line, in almost heaven, as am I? ;D
DNA has its own language (code), and language requires intelligence. There is no known mechanism by which matter can give birth to information, let alone language. It is unreasonable to believe the world could have happened by chance.
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Re: The P value

Post by WiseOne » Thu Apr 26, 2018 7:49 am

Hey, don't knock roadkill.

In Alaska, some towns maintain a list of families most in need of food. Whenever a road kill moose happens, the town calls the next family on the list to come get it. I heard this story at a potluck in the Kenai Peninsula where I was enjoying a stew made from...you guessed it, road kill moose. Yummy.

Beats food stamps, eh???
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Mountaineer
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Re: The P value

Post by Mountaineer » Thu Apr 26, 2018 8:07 am

Make your reservations now. Get ready for some culinary excellence. :)

Play this while making your reservation: https://www.youtube.com/watch?v=1vrEljMfXYo

https://www.wherevent.com/detail/West-V ... t-Festival

The West Virginia RoadKill Cook-off is one of the region’s most fun and exciting annual events. In years past, the Food Network, the Travel Channel and the Discovery Channel have all covered this wild and offbeat festival! If you’ve ever wanted to taste exotic dishes like squirrel gravy over biscuits, teriyaki-marinated bear or deer sausage, this is the place to be!

Friday night is the Rockin Redneck Square dance and Saturday is the Roadkill Cookoff!
DNA has its own language (code), and language requires intelligence. There is no known mechanism by which matter can give birth to information, let alone language. It is unreasonable to believe the world could have happened by chance.
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jhogue
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Re: The P value

Post by jhogue » Thu Apr 26, 2018 12:40 pm

On Grandpa's farm, we only ate what we killed ourselves. Anything else was only fit for the dogs.
“Groucho Marx wrote:
A stock trader asked him, "Groucho, where do you put all your money?" Groucho was said to have replied, "In Treasury bonds", and the trader said, "You can't make much money on those." Groucho said, "You can if you have enough of them!"
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