Re: Roberts versus Lazio on "Overaveraging"

From: Bill Rowe (readnewscix_at_earthlink.net.invalid)
Date: 01/29/05 

Date: Sat, 29 Jan 2005 05:37:41 GMT

In article <KXwKd.6770$VA5.4966@fe07.usenetserver.com>,
 "greywolf42" <mingstb@marssim-ss.com> wrote:

> Bill Rowe <readnewscix@earthlink.net.invalid> wrote in message
> news:readnewscix-44350F.22020227012005@news1.west.earthlink.net...
> > In article <LnzJd.6297$VA5.1171@fe07.usenetserver.com>,
> > "greywolf42" <mingstb@marssim-ss.com> wrote:

> > > Bill Rowe <readnewscix@earthlink.net.invalid> wrote in message
> > > news:readnewscix-871AD6.23104719012005@news1.west.earthlink.net...

> > <snip>
 
> > > > Do you have any familiarity at all with basic statistics? In
> > > > particular the central limit theorem? If so, it should be
> > > > immediately apparent Tom's claim above is a direct
> > > > consequence of the central limit theorem.
> > > > And if you are not familiar with it pick up any reasonable
> > > > basic text on statistics, go to the index or table of contents
> > > > and find central limit theorem and turn to the referenced page.

> > > So sorry, but the central limit thoerem has nothing to say about taking
> > > data beyond the physical capabilities of the apparatus.

> > And my comments in no way imply the central limit theorem or any
> > mathematical theorem has anything to say about the methodology of taking
> > data. Such an assertion would be totally inane.

> Then why did you bring it up, when the subject is taking data below the
> physical resolution of the apparatus?

Roberts made a remark that results from an application of the central
limit theorem and ascribed it to "Data Analysis 101" You seemed unaware
of the basis for the remark, hence my comment.

> > But the central limit theorem does apply to analysis of data. In
> > particular, it tells you what you should expect when you average
> > statistically independent samples take from a distribution that has a
> > finite mean and finite variance. And that is what is applicable here.

> There is no "finite mean" or "finite variance" on the data under discussion.
> Both are indeterminate. That is the point. Neither can be determined.
> Hence, the CLT can't be applied.

What are you talking about? Unless you have a rather unusual situation,
the distribution of data values has a finite mean and finite variance
and the central limit theorem does apply.

<snip>
> > > LOL! While computers always do things exactly the same way. So they
> > > never achieve statistical independence, either?

> > From this, I assume you've no knowledge of quantization uncertainty,
> > random noise etc that cause the least significant digits of a digital
> > meter to vary.
 
> A total red herring -- as noted several times before.

The point being digital instruments do not get the same reading for
every measurement. That is your " LOL! While computers always do
things exactly the same way" either is totally not relevant or is a
result of a lack of understanding of how such instruments work.

> > I also assume you've not familiarity with chaos theory
> > where one gets unpredictable results using a deterministic algorithm on
> > a computer.

> Only if you build such into the program. Even "random" functions are not
> random, in a computer.

Random has always been in the eye of the beholder. So, your observation
here has little relevance to the topic at hand.
 
> > In short, if you really believe what you wrote and imply,
> > you clearly have little knowledge regarding what you are writing about.

> Pure special plead. Zero content.

Not at all. An observation on the relevance of your comments to the
topic at hand.
 
> > > > Certainly and observer can move his viewpoint. But this isn't much of
> > > > a solution in practice. Basically, what one would do is move your
> > > > viewpoint until you got what you thought was the best reading.

> > > Huh? Didn't anyone train you how to avoid optical parallax when taking
> > > readings? You don't look for the "best" reading, but the middle of the
> > > two extremes. Net result is no optical parallax error.

> > And you apparently do not realize when someone does "the middle of the
> > two extremes" they do this in a manner that is not independent of the
> > observer and has certain bias built in that is unavoidable.
 
> Absolute B.S. Also unsupported.

> Bias is not the result of optical parallax.

So? I've not said bias is the result of optical parallax. I do say
humans have a profound tendency to do things in the same manner. As a
result, attempts to select the middle position when attempting to
eliminate optical parallax simply are not uncorrelated an often have
some unintended bias. This is simply the nature of humans. And this is
exactly what Tom Roberts has referred to in the past as experimenter's
bias. It is a real, non-zero effect that is unavoidable.

<rest snipped as overly repetitive and previously addressed> 

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Relevant Pages

  • Re: Roberts versus Lazio on "Overaveraging"
    ... Such an assertion would be totally inane. ... the distribution of data values has a finite mean and finite variance ... An observation on the relevance of your comments to the ... I've not said bias is the result of optical parallax. ...
    (sci.physics.relativity)
  • Re: Roberts versus Lazio on "Overaveraging"
    ... Such an assertion would be totally inane. ... the distribution of data values has a finite mean and finite variance ... An observation on the relevance of your comments to the ... I've not said bias is the result of optical parallax. ...
    (sci.physics)