Thanks for letting me know I am not the only one with this problem.
Reading all the responses reminded me that I have a definition of human
error that might be shared by others, but might be different than some
ideas posted here.
I believe human error only includes blunders... mistakes. I do not
believe human error is reaction time using a stop watch, or the last
estimated digit when reading a scale. The interaction between the human
and the instrument has a typical amount of uncertainty even when used
correctly. Assuming the person is using the device correctly, this
uncertainty is not human error. It's just the way the instrument is
designed to interface with humans.
If I am using a meter stick accurately ruled to the millimeter, and I
estimate to a tenth millimeter and say my measurement is +-0.1 mm, this
uncertainty is not human error. It is just the inherent uncertainty for
using this type of instrument. Likewise, when I use a micrometer having
a barrel ruled to the hundredth millimeter and I estimate to the
thousandth millimeter, the uncertainty of +-0.001 mm is not human error.
However, if I need to measure the thickness of something to within
+-0.01 mm, and I use a meter stick to do it, that is a human error... a
blunder. The wrong instrument was chosen.
Even if a student says, "I can only read the meter stick to within the
nearest millimeter, but others estimate better than I, so isn't my
result human error?" I say, "If you cannot get the kind of reading you
need using the tool you are using, human error will occur if you fail to
switch to a tool that enables *you* to get the kind of precision or
accuracy you need."
A statement I often repeat to the students goes like this. If you
determine it is a problem that you are only making measurements to the
nearest millimeter and you need measurements to the nearest
tenth-millimeter... you don't need a different human... you need a
different instrument.
What are other human errors? Failure to calibrate an instrument that
requires calibration. Failure to use the instrument properly.
Continuing to use an instrument that appears to be malfunctioning.
Writing the measurement incorrectly in the lab notebook, for example
misplacing the decimal point or transposing two digits. Writing
illegibly. Failure to write down the scale and units of the instrument
you're using.
In the end, human errors are not tolerable. That doesn't mean they
don't occur... it just means they are supposed to get fixed before you
publish your paper. Having said that, I liked John Denker's response
that students are sometimes in situations where they don't have the
opportunity or time to fix human errors. I agree with that. Of course,
if you ask my students, especially near the end of the term, they don't
have time even to do the lab once, let alone repeat it.
Michael D. Edmiston, Ph.D.
Professor of Physics and Chemistry
Bluffton University
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu
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