[Phys-L] Re: infinite sig. figs.

[John Denker <jsd@AV8N.COM>]

I agree with what Michael E. wrote
   http://lists.nau.edu/cgi-bin/wa?A2=ind0509&L=phys-l&F=&S=&P=47801
and indeed he expressed what I really believe better than I did.

Let me expand on one passage:
> He went on to say that if you don't specify a tolerance then the typical
> machinist will assume +/- 1 in the last digit specified...

There are a couple of additional lessons to be drawn from what the
master machinist _did_, in contrast to what he _said_ about the
"typical" machinist.

1) If I got a specification of the form 5.000 inches, with no other
information, I would take it as a sign that the specifier didn't
know what he was doing.  I would go back to the guy and find some
way of teaching him to do things right.

This is exactly what the master machinist did!  This is also the
#1 recommendation that I provide in my discussion of how to survive
an attack of the sig figs:
   http://www.av8n.com/physics/uncertainty.htm#sec-survival

2) The master machinist's final recommendation did *not* involve
relying on any form of sig figs!  Instead he recommended stating
the tolerance separately and explicitly.  This is what I have been
recommending at
   http://www.av8n.com/physics/uncertainty.htm#sec-rec

=================

People who know what they are doing state the uncertainty (or tolerance,
or significance) separately and explicitly.

If you don't do it this way, people will rightly assume you don't know
what you are doing.
_______________________________________________
Phys-L mailing list
Phys-L@electron.physics.buffalo.edu
https://www.physics.buffalo.edu/mailman/listinfo/phys-l