10
Calculating the Standard Deviation
Calculate the standard deviation using a suitable calculator or according to
the following formula:
Evaluation: The value calculated in this way must be within the permissible tolerances for
reproducibility (standard deviation) given on the Service Specifications Sheet.
If the standard deviation calculated in this way is too high, carry out the
following tests:
– Are the requirements listed under “Place of Installation” and “Getting
Started “ met?
– Recheck the permissible off-center loading tolerances.
– Clean the weighing system and make sure that there is no friction between
the movable parts. (Friction between movable parts causes unstable
weighing results.)
Recheck the reproducibility (standard deviation) as described in the section
“Checking the Reproducibility.”
Checking the Off-center Loading Tolerances
Test Weights: (E2 - individual weights, nominal values)
Model Test weight
RC210S/P/D 100g
RC250S 100g
MC210S/P 100g
MC410S 200g
Test Procedure (Weighing)
1) Center the test weight on the weighing pan and tare the balance.
2) In the order given in the Balance Test Record, place the test weight in
each of the off-center positions indicated and write down the weight on
the Balance Test Record.
3) Repeat steps 1) and 2) for all off-center loading positions.
Evaluating the Test Results:
The value obtained for each off-center loading position must be within the off-
center loading tolerances given in the Service Specifications Sheet.
If the off-center loading error is too large, adjust the balance so that the off-
center loading error is within the tolerances specified.
x
i
= Individual weighed values
= mean value of the
Individual weighed values
n = Number of weighings (6)
s
n
x
i
i
n
x=
−
=
−
∑
1
1
1
2
*
()
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