Fisher FERITSCOPE FMP30, Руководство оператора

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Operator‘s Manual FERITSCOPE
®
FMP30 Page 225
Glossary
ment result generally obtained under practical conditions.
(
Tolerance limits (Specification limits) Specification limits (LSL and
USL); for detailed information, see / 20 /.) The true value is a value
known from mathematical theoretical formulations. Since such values
are seldom encountered, a value deduced from national or interna-
tional standards is taken as “right”. This right value is often called
the true value.
True value Trueness (Accuracy of the mean)
Tolerance limits (Specification limits) Specification limits (LSL and USL)
Two-point calibration Corrective calibration (one-point or two-point
calibration)
u
Uncertainty of measurement. The mean value Fe. of a random sample is
not equal to the mean value

of the population. However, using the
measurement uncertainty, it is possible to define an interval, in which
the mean value

of the population will be found with a certain proba-
bility (indicated as confidence level):
For a population having normal distribution, the uncertainty of measure-
ment u is calculated as follows for a given confidence level (1-

):
By entering the coefficient of variation C.O.V. in place of the standard
deviation s one gets the relative measurement uncertainty u
rel
in %. (For
further details, see / 12 /.)
Uncertainty of measurement u
Uncertainty (k=2)
Parameter in the result display in the function CAL-Check. It states the meas-
urement uncertainty of the calibration of the open application file (measure-
ment accuracy of the open application file). This combined measurement un-
Fe. u –

Fe. u +
 
u
t s

N
-------- =
where: u = measurement uncertainty
t = student factor
s = standard deviation
N = number of readings
u
rel
t V

N
---------- =