OHAUS TROOPER, Service Manual

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4-3
CHAPTER 4 TESTING
Reading Weight (kg) Weight - Mean (Weight – Mean) 2
1
2
3
4
5
6
7
8
9
10
SUM = SUM =
Mean = SUM/10 Variance = SUM/9
Mean = = = = = = Variance
=
=
= =
=
Figure 4-4. Calculation of Standard Deviation ( ).
Reading Weight (kg) Weight - Mean (Weight – Mean)
2
1 (3) (4)
2 (3) (4)
3 (3) (4)
4 (3) (4)
5 (3) (4)
6 (3) (4)
7 (3) (4)
8 (3) (4)
9 (3) (4)
10 (3) (4)
SUM = (1) SUM = (5)
Mean = SUM/10 Variance = SUM/9 (6)
Mean = =
= =
= (2) = Variance
After recording the ten weight readings in the Weight column perform the following steps:
1. Record the sum of the ten weight readings here.
2. Record the Mean (Avg) of the ten weight readings here. (SUM divided by 10)
3. For each weight reading, subtract the calculated Mean and record the result.
4. For each weight reading, record the square of the (Weight – Mean) from step 3.
5. Record the sum of the squared (Weight – Mean) values from step 4.
6. Record the Variance of the ten weight readings here. (SUM divided by 9)
7. Record the Standard Deviation of the ten weight readings here. (square root of the
Variance)
σ
σ
√
σ
σ
σ
σ
√
= (7)
4.3.1 Repeatability Test (Cont.)
Figure 4-3. Standard Deviation ( ) Worksheet.