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[Phys-L] Re: fall cleanup: sig figs



John Denker writes:

The notion of "sig figs" is garbage.

Hear, hear!

If anything, John understates the situation. Uncertainty needs to be
addressed, and if a numerical result is stated in a teaching
laboratory or recitation problem it should be accompanied by an
explicit uncertainty. This latter quantity will usually be different
from the implicit uncertainty in the data given the student in a
particular problem. The fact that there is an implicit uncertainty
must be told to the student too. Uncertainty needs to be
distinguished from error, and the latter must never be characterized
as the discrepancy between the student's measurement and what is
listed in the rubber bible. There are many incipient opportunities
for conceptual confusion in these topics; they are a minefield of
misconception.

What students need to be told is that many of their digits are
insignificant. That is not best achieved by blessing some digits as
being "significant".

Leigh