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From: thomas@utah-gr.UUCP (Spencer W. Thomas)
Newsgroups: net.med
Subject: Re: The Perils of Nutrasweet: digits of precision
Message-ID: <1542@utah-gr.UUCP>
Date: Mon, 5-Aug-85 15:48:36 EDT
Article-I.D.: utah-gr.1542
Posted: Mon Aug  5 15:48:36 1985
Date-Received: Sun, 11-Aug-85 03:46:10 EDT
References: <771@burl.UUCP> <394@petrus.UUCP> <182@steinmetz.UUCP>
Reply-To: thomas@utah-gr.UUCP (Spencer W. Thomas)
Organization: Univ of Utah CS Dept
Lines: 20
Summary: 


In article <622@ttidcc.UUCP> hollombe@ttidcc.UUCP (The Polymath) writes:
>I agree. 10% has only one significant  digit,  but  .007%  has  three.  The
>decimal  point  makes the two leading zeros significant (i.e.: the original
>article claims accuracy to three decimal places).
>
The original article may claim accurace to 3 decimal places, but the way
I learned significant digits, you should write 0.00700% to specify 3
digits of accuracy.  10% is a toughie - you really can't tell whether
the meaning is 10%+/-5% (1 digit) or 10%+/-.5% (2 digits).  For 3
digits, you should write 10.0%.  The best way to write numbers to
clearly specify the number of siginificant digits is to use scientific
notation.  Thus:
	1 digit		3 digits
	7e-3		7.00e-3
	1e+1		1.00e+1

-- 
=Spencer   ({ihnp4,decvax}!utah-cs!thomas, thomas@utah-cs.ARPA)
	"You don't get to choose how you're going to die.  Or when.
	 You can only decide how you're going to live." Joan Baez