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Re: Linearizing Graphs



In response to John Cooper mentioning a graph of residuals....

Gosh, you mean ask the students to make two graphs?

Actually, I had not thought of that. And it's a very good idea. But
it will be interesting to see what the students think about me
increasing the expected work. I am amazed that today, when students do
not have to plot by hand, they still ask... do we really need to make a
graph?

Michael D. Edmiston, Ph.D. Phone/voice-mail: 419-358-3270
Professor of Chemistry & Physics FAX: 419-358-3323
Chairman, Science Department E-Mail edmiston@bluffton.edu
Bluffton College
280 West College Avenue
Bluffton, OH 45817



-----Original Message-----
From: John Cooper [SMTP:jcooper@BUCKNELL.EDU]
Sent: Wednesday, October 20, 1999 10:42 AM
To: PHYS-L@lists.nau.edu
Subject: Re: Linearizing Graphs

On Wed, 20 Oct 1999, Michael Edmiston wrote:

(2) If we are trying to determine if the equation (the theory) is
upheld by the data, it is much easier to judge (by eye) if the data
points form a straight line, than to determine if they follow a
specific curve.
Have you thought of plotting residuals of a function from the data,
or
vice versa? Such a residual plot against the independent data gives an
immediate visualization of the deviation from the proposed fit, whether
that proposed fit is linear or not, and strongly suggests possible
modifications of the fit.
The Durbin-Watson statistic provides a numerical indicator that
semi-
quantifies the distribution of the residuals, whether ~random,
systematically deviant.