Re: Significant figures - a Modest Proposal

[Richard Tarara <rtarara@SAINTMARYS.EDU>]

----- Original Message -----
From: Leigh Palmer <palmer@SFU.CA>
To: <PHYS-L@lists.nau.edu>
Sent: Monday, August 30, 1999 9:26 AM
Subject: Re: Significant figures - a Modest Proposal


> At 06:03 -0700 8/30/99, Robert A Cohen wrote:
>
> > While I'm on the topic, I should mention that I will be emphasizing the
> > distinction between precision and resolution and that both contribute to
> > the accuracy of the measurement (I haven't done so in the past).  The
> > activity above is designed to introduce the idea of resolution and its
> > effect on calculations.  The second activity is designed to introduce the
> > idea of precision and its effect on calculations (they time cars and see
> > how many are speeding - the timer provides measurements to the hundreths
> > of a second but the precision is not that good).  If anyone has any
> > experience with teaching this, I'd appreciate pointers.
>
> Please amplify this somewhat. I think I have always treated resolution
> and precision as being nearly identical in meaning. What are your views
> on that topic, which I do consider to be very important?
>
> Leigh

I've never quite been sure of the correct words to use, but I think one
wants to separate the precision to which a measurement CAN be made (limited
by the instrument used) and the accuracy to which the measurement is
actually made (limited by the care and/or skill or the person).  For
example, a very good ruler might be capable of measurements to within a few
tenths of a millimeter, but sloppy technique can limit it's accuracy (using
the end of the ruler as zero--for example) to a few millimeters.  Students
often don't even attempt to make measurements to the maximum precision of
their instruments.  Again, I'm not sure of the correct nomenclature (if
there is one) for this difference.

Rick

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Richard W. Tarara
Department of Chemistry & Physics
Notre Dame, IN 46556
219-284-4664
rtarara@saintmarys.edu

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