RADIOMETER ABL800 FLEX, Reference Manual

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ABL800 FLEX Reference Manual 5. Performance characteristics
Definition of terms and test conditions,
Continued
Reproducibility Reproducibility is obtained from repeated measurements within several days using:
•
Random instrument
•
Random sample
•
Random operators.
Reproducibility for each level is pooled for all test instruments and test days.
Total variation
range
The total variation range is given as
±
2
×
S
X
, where S
X
is the reproducibility.
Imprecision Repeated measurements using one analyzer on samples assumed to be identical
will not necessarily yield identical results. The degree of variation in the results is
a measure of the precision of the analyzer.
The following table describes the parameters used to characterize precision
obtained via the performance tests on the ABL700 Series of analyzers.
Parameter Description
S
0
Repeatability
This is a standard deviation obtained from repeated
measurements within a short interval of time using:
•
The same instrument and location
•
The same measurement procedure
•
Identical portions of the same sample
•
One operator per instrument
S
0
for each level is pooled for all test instruments and test days.
S
D
Day-to-day variation
This is a standard deviation obtained from repeated
measurements over all test days.
Includes contributions from differences in calibration states of the
analyzers throughout the test days.
S
ABL
Uncertainty of bias on a random instrument
S
ABL
is used for repeated determinations on one sample. This
standard deviation includes the inter-instrument variations,
sample variations, and uncertainties from standard solutions and
reference methods.
S
X
Uncertainty of bias on a random instrument for a single
measurement
S
X
is a standard deviation which includes S
ABL
, S
D
and S
0
.
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