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Re: [Phys-l] formatting uncertainties

On 01/23/2008 09:24 AM, Rick Tarara wrote:


... I suspect that the primary thing most instructors
are dealing with is students multiplying two values on their calculators and
then writing down every digit that appears.

Is that a problem? Why should that be a problem? Tell me,
please, who is harmed by those "extra" digits? How does the
cost of keeping "extra" digits compare to the cost of keeping
too few digits?

IMHO one rule should be don't round off unless you are sure it
is safe. And the typical HS student will rarely have a good
feel for what is safe and what is not. The teacher may step
in and tell them that in a certain problem it is safe to
round off to N digits ... but N will vary from problem to
problem ... and there should never be a penalty for keeping
more than N digits.

Teaching any more-aggressive roundoff rules is a waste
of time and effort in the short run, and is even worse
than that in the long run, because such rules will just
need to be unlearned later.

My answer is that these ARE high school students--and high school teachers.
All of the experimental and statistical subtleties that John brings up are
beyond the HS curriculum. I know JD thinks they shouldn't be,

Maybe, maybe not.

What I will say is that high-school teachers need to have more
than a high-school education. That's so that they can ascertain
what should be taught as the /foundation/ for further work, and
ascertain what to avoid because it is nonsense that will have to
be unlearned later.

Let me put it another way...when did each of us actually have a statistics
course? If like me---never.

I've never taken a statistics course. I've never taken a
computer science course, either. I've taught them, but never
taken them.

When I plot the distributions in the usual way, the difference
between .67255 ± 0.001 and .6726 ± 0.001 is readily perceptible
to the naked eye. If somebody is unable to perceive the difference,
that's his problem, not mine.

I confess to having the above problem--OK, maybe if I actually saw the
plots--but I don't know from this what I should expect to see. Sure, that's
my problem, but I suspect one shared by many here. ;-)

Fair enough.
http://www.av8n.com/physics/img48/grav-roundoff.png