The one time I commonly use percent is just after students have tried to
verify a prediction they made. Recently, they came up with Ohm's law from
plotting voltage vs current for different resistors. I then had them
predict what would happen with resistors in series. When talking about
the initial measurement, they often resort to comments about the absolute
difference between their experimental value and their prediction, i.e. "I
was only off by a 2.4 mA." I then might ask is that a large or small
difference relative to their prediction. Otherwise, we stick to using
standard deviation to either reject or not reject their hypothesis.
Scott Rippetoe rippetoe@tenet.edu
Academy of Science and Technology voice (713) 292-2615
27330 Oak Ridge School Road fax (713) 298-3292
Conroe, Texas 77385