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From: Jacob Sparre Andersen <sparre@nbi.dk>
Newsgroups: comp.lang.ada
Subject: Re: OT: definition of "significant figures"
Date: 01 Aug 2005 09:31:28 +0200
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Date: 2005-08-01T09:31:28+02:00
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Adrian Wrigley wrote:
> On Fri, 29 Jul 2005 16:46:36 +0200, Jacob Sparre Andersen wrote:
> > tmoran@acm.org writes:

> >> Given a set of measurements x(i), I'd like to print their average
> >> to the "correct" number of significant figures.  eg 1.11, 1.12,
> >> 1.08 => "1.1", 1.11, 1.25, 1.35 => "1" I've got some adhocery
> >> that more or less does it, but is there a moderately standard,
> >> formal, definition?
> > 
> > The base 10 logarithm of the standard-deviation of your measurements.
> 
> this looks like one of those physicist's sign errors!

I know. ;)

> How about:
> 
> *Minus* the base 10 logarithms of the standard deviation =>
>   *decimal places*

Yes.  Apparently I didn't even understand the question.

> For example:
> SD=0.1   => use 1 decimal place
> SD=0.001 => use 3 decimal places
> 
> Note that decimal places are not significant figures!

Yes.

> Significant figures = Log10 (mean / standard deviation) + C
> 
> I think people also add in the (small) constant, for good measure,
> depending on how they feel about the data distribution.

Yes.

Jacob (who should start thinking before he posts)
-- 
Growing older is compulsory. Growing up isn't.