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From: jin@hropus.UUCP (Bear)
Newsgroups: net.sci
Subject: Re: Adding Standard Deviations
Message-ID: <357@hropus.UUCP>
Date: Mon, 17-Mar-86 09:05:19 EST
Article-I.D.: hropus.357
Posted: Mon Mar 17 09:05:19 1986
Date-Received: Tue, 18-Mar-86 07:49:38 EST
References: <1794@sphinx.UChicago.UUCP> <12410@ucbvax.BERKELEY.EDU>
Organization: Bell Labs, Holmdel, NJ
Lines: 20

> >From: ihnp4!gargoyle!sphinx!fdot (Tom Lippincott)
> >
> >How about error handling?  I've never seen *any* program where you could,
> >for example, add 1.23+/-.02 to 4.56+/-.04 and get 5.79+/-.06, let alone
> >perform more complicated math, graph them with error bars automatically, etc.
> 
>    Maybe that's because (1.23 +- .02) + (4.56 +- .04) = (5.79 +- .045)?
> (Or do you want the program to figure out the correlation coefficient? :-))
> 
>    -- David desJardins

If I remember my stats correctly the sum of two error intervals is the
square root of the sum of squares only if the two measurements are
non-correlated.  I don't know the context of this discussion but thought
I'd drop my .02$ in.
-- 
			Jerry Natowitz
			ihnp4!houxm!hropus!jin (official)
			ihnp4!opus!jin         (temporary) 
			Institute for the Study of Non-existent Phenomena