Metrohm 870 KF Titrino plus Manual - Manual (Page 91)

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10 Appendix
870 KF Titrino plus
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Rounding-off process
Measured values and results are rounded to the defined number of deci-
mal places (commercial rounding, in accordance with the US Pharmaco-
peia USP). If the digit at the first dropped decimal place is 1, 2, 3 or 4,
then it will be rounded off; if this digit is 5, 6, 7, 8 or 9, then it will be
rounded up. Negative digits will be rounded in accordance with their
amount, i.e. away from zero.
Examples:
2.33 yields 2.3
2.35 yields 2.4
2.47 yields 2.5
–2.38 yields –2.4
–2.45 yields –2.5
Statistics
The arithmetic mean value and the absolute and relative standard devia-
tions of results are calculated:
You can statistically evaluate a maximum of five results (1 ≤ k ≤ 5) calcu-
lated in a determination. A statistical series can contain a maximum of 20
determinations (1
≤ n ≤ 20).
The following convention applies to the subsequent formulas:
1 ≤ n ≤ 20 and 1 ≤ k ≤ 5.
Mean value:
Absolute standard deviation:
Relative standard deviation (in %):
Explanations
The individual values are incorporated in the statistics with full accuracy.
15 significant places are yielded when the 64 bit numerical format is
applied for the floating-point number in decimal presentation.
The accuracy can be controlled by the selection of the prefix of the unit
(milli, micro) and the number of decimal places.
Example: