Re: what good is "percentage error"?

[Richard Goode <rgoode@porterville.k12.ca.us>]

Quist, Oren Phys wrote:
> The student needs some way of comparing his answers to acceptable values,
> but should not expect to get those values due to inabilities to control
> all of the necessary variables adequately.
>
> Students often think of physics as and "exact science," when it is really
> just the "science of approximations."  We usually can be as accurate as
> we want, but do not have the wherewithall (especially financially) to be
> as accurate as students sometimes come to expect.

I agree with the "science of approximations" idea. In my high school level 
course I have them find their percent deviation to verify their own technique. 
Many times in previous science courses they have not had to be accountable 
their own efforts.  This allows them to verify abilities and to understand the 
limits of equipment. If they get an unusually high deviation, I have them 
analyze the experiment to determine where the deviation occured. I also have 
them compare experimental results with other groups to see if someone else can 
duplicate the deviation. 

I think there is something useful here we can use to teach how to experiment, 
not necessarily how wrong they are. Experimental analysis is not easy to 
convey. It is hard to get them to ask: Where could I haved erred?, instead of 
What is the right answer?

  

-- 
Richard Goode
Physics Teacher
Porterville High School

"Man does not cease to play because he grows old;
	Man grows old because he ceases to play."