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Re: resolution vs. precision



I think there is a difference between resolution and precision (and
accuracy).
* * * * *
I equate resolution with readability. What is the smallest incremental
reading the instrument can make? The stop-watch feature of a digital
wrist watch usually has a resolution of 0.01 s.
* * * * *
I equate precision with reproducibility. How small is the standard
deviation of a series of measurements of the same thing?

Poor precision can be partly instrumental, partly measurement
technique, and partly nature.
-- Instrumental: some inexpensive digital stop watches start/stop with
variable pressure on the pushbutton. This is a case of sloppy
PB-switch construction, and it can make it difficult to achieve high
precision.
-- Technique: if I change timer activation from my finger to my thumb,
or left hand to right hand, or person to person, (within a series of
measurements of the same thing) then variable technique can lead to
poor precision.
-- Nature: if I am timing an air track glider going from the 30-cm mark
to the 60-cm mark after being launched by a rubber-band launcher,
successive launches might not yield equal velocities; i.e. the thing
being measured does not behave reproducibly, and this shows up as poor
precision.
* * * * *
I equate accuracy with fidelity to established standards. If the
quartz crystal of the stop watch is supposed to oscillate at 10.000 MHz
but is oscillating at 10.002 MHz, we have an accuracy problem.


Michael D. Edmiston, Ph.D. Phone/voice-mail: 419-358-3270
Professor of Chemistry & Physics FAX: 419-358-3323
Chairman, Science Department E-Mail edmiston@bluffton.edu
Bluffton College
280 West College Avenue
Bluffton, OH 45817