About Random Errors in Measurements
About random errors in measurements
Random errors are perturbations of the measurement either side of the
true value caused by random and unpredictable effects, such that
positive errors and negative errors occur in approximately equal
numbers for a series of measurements made of the same quantity. Such
perturbations are mainly small, but large perturbations occur from
time to time, again unpredictably. Random errors often arise when
measurements are taken by human observation of an analog meter,
especially where this involves interpolation between scale points.
Electrical noise can also be a source of random errors.
To a large
extent, random errors can be overcome by taking the same measurement a
number of times and extracting a value by averaging or other
statistical techniques. However, any
quantification of the measurement value and statement of error bounds
remains a statistical quantity. Because of the nature of random errors
and the fact that large perturbations in the measured quantity occur
from time to time, the best that we can do is to express measurements
in probabilistic terms: we may be able to assign a 95% or even 99%
confidence level that the measurement is a certain value within error
bounds of, say, ±1%, but we can never attach a 100% probability to
measurement values which are subject to random errors.
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Measurement System Errors
