3.
DEFINITION AND ORDER OF TREATMENT OF ERRORS.
a. Error is defined as the difference between the true value of a
quantity and its measured or calculated value.
(1) Quantitative error is error expressed in units of measure,
(2) Percentage error is the ratio of the quantitative error of an
instrument being calibrated.
b. Errors are treated in the following order:
(1) Prevention - by using correct equipment and procedures.
(2) Reduction - by careful analysis of the meter readings, attention
to details, and being alert for unusual readings or conditions.
(3) Allowance - by making correction charts, temperature charts, etc.
4.
TYPES AND TREATMENT OF ERRORS.
a. Types of errors. In discussing errors from the standpoint of types,
we are more concerned with the ways in which these types of errors affect
the accuracy and/or precision of the measurement than with the ways in which
they were caused. This leads us to the consideration of three major types
of errors: gross, systematic, and random.
b. Gross errors. Gross errors are those caused by the operator. These
errors are sometimes called mistakes and consist of errors of arithmetic,
misplacement of decimal points, transposition of figures, reversal of sign,
recording of a figure of a wrong value, reading the scale Wrong, improper
connections, or the disregard for known errors of other types. Gross errors
also result from the use of the wrong
instruments and from making
unrealistic assumptions regarding the factors involved in the measurement
setup (procedure).
(1) Causes.
(a) Improper use of equipment.
(b) Careless operation of equipment.
(c) Use of faulty equipment.
(d) Failure to follow valid (written) procedures.
(e) Mistakes in computation and transcribing figures.
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