The purpose of statistics is to project the possibility or the probability

of a given event occurring in the future. With Periostat, this means what is

the chance of a good outcome, say meaningful pocket reduction.

The data is obtained from a specific population, say 100 or 1,000 people.

The general population is 6 billion. We need a way of predicting possible

outcomes.

That is the purpose statistics or inferential analysis.

********

Newsgroups: sci.med.dentistry

Subject: Re: Perio treatment

Date: Mon, 23 Apr 2001 05:38:03 GMT

Organization: EarthLink Inc. -- http://www.***.com/

Quote:

> Joel, how do they deteremine the P value? ie. (P>0.05) I was under the

> impression that P values were of more value because the took into

> consideration standard deviation. This is what all the clinical trial

> studies seem to use. Is there something you know that the reviewers

don't?

**********

P value. I wll send another post about this tomorrow. It is a slightly

complicated issue why this is so.

**********

Quote:

> ******

> I'm confused. I asked you how P values are determined, not standard

deviation. You clearly have a vast knowledge of statistical calculation,

could you please explain the P value?

****

Tomorrow .....

*****

I have a vague impression that cement A works well in my hands. As

Quote:

> for patient response to cement A, how would I eliminate confounding

> variables?

I don't understand your question.

*****

Meaning, is cement A better, or is it that it only is better due to some

other unmeasured variable, that is occurring only in my office? This means

that cement B may be in fact, the better cement.

***********************

Quote:

> If you can't trust the research, and you can't trust you own observations,

> what can you do?

> Read Reality, CRA, etc.

Please be more specific. What is the "etc?" Are these publications that

can be trusted to provide more accurate and reliable clinical information

than those that typical dentists and periodontists rely on?

*****

These publications come the closest to a "Consumer Reports: type of

independent assessment of various materials.

Quote:

> Same with golf scores, same with Periostat data.

> Std. Deviation - an unknown to your golfing buddy!

Did a little research on my own....standard deviation takes on importance

only when you lack a control....double blind study, and the control is

valid, Std. Deviation takes on far less significance.

********

Stardard deviation tells people how far the measurement deviates (deviation)

from the mean (from the average). This is very valuable. I suspect that the

Periostat data has a very low standard deviation (meaning the data closely

follows the mean or average).

Your golfing buddy predicts a large standard deviation, meaning that the

average is one-half the thickness of a dime, while several patients of his

obtain three dime''s thickness worth of improvement.

********

Your analogy fails because the golf scores have no control to compare. When

the control and the subject are both placed under the same conditions, then

measured by the same standard, the control is considered zero and the

variance between the control and the test subject is the result.

P value is the probability of a given variance happening as a result of the

tested hypothesis.

He says he sees less bleeding, less pocket depths,

and less non-responding pockets when a patient is prescribed Periostat

and is compliant and faithful in taking the medication.

He is probably fooling himself .... or more likely, his patients!

Quote:

> Ah, so based on his observations, he is either incompetent or unethical?

Well Joel, which is it?

**************

No, I think he is not really that interested in whether or not it works. He

just does what he does. It does not harm anyone so why not do it anyway?

That is the attitude of most.

I am just being a bit more rigorous to encourage better and more effective

therapies.

Joel M. Eichen, D.D.S.

Mailgate References:

Perio treatment, Joel M. Eichen

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