TEXT
1.
INTRODUCTION.
a. All of your life you have made measurements; and you knew all along
that the accuracy of a measurement was determined, to a great extent, by the
care taken to reduce the errors that were associated with the measurement.
These errors are of many kinds and are the results of a great many causes.
No measurement has ever been made that did not contain an error.
If we
define measurement error as the difference between the actual size of an
object and the size we measure it to be, then the smallness or the error
involved in the measurement will be limited by the resolution of our
measuring instrument.
The probability of hitting on the exact figure by
pure chance is very remote since the true size of the object would have to
be expressed in an infinite number of decimal places.
b. The goal is to reduce the errors to a low value or to reduce the
probability of their occurrence to a minimum and to determine the amount of
error, if possible, because we know that we cannot remove or eliminate all
error. To achieve this goal, you must have considerable knowledge about the
nature and types of measurements and causes of errors.
c. Errors will exist no matter what you do. It is very important to
learn how to reduce errors to negligible size or to find out exactly how big
they are so that you can allow for them. The goal is to reduce errors and
get more dependable measurements.
The attitude of the calibration
specialist toward his work is as important an ingredient as is his control
over the methods, equipment, and environment.
Before we can do anything
constructive about reducing errors, we must know one or more of the
following:
(1) What errors are likely to exist.
(2) How large they are likely to be.
(3) What errors do exist.
(4) How large are they?
d. As you progress in the field of metrology, you will find a need for
a penetrating analysis of measurement.
Indeed, the accuracy of your
measurements will depend upon your skill in the control of these errors.
e. Significant figures, when improperly used, tend to imply that an
error is absent when it is actually present. The use of significant figures
is common throughout the area of measurement.
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