Mitutoyo DP-1VA LOGGER - Formulas

76
7Specications
No. 99MAM029A
7.2.2 Formulas

Calculation of MODE1 and MODE2
Print Meaning Calculation formula
N Number of data
MAX Maximum data value
MIN Minimum data value
R Data range MA X−MIN
X¯ Average data value ΣXi/N
σn Standard deviation σn = ((N•ΣESXi
2
− (ΣXi)
2
) / N2)
1/2
σn-1 Sample standard deviation σn − 1 = ((N•ΣESXi
2
− (ΣXi)
2
) / N•E(N − 1))
1/2
−NG
Number of data lower than the
lower specication limit value
Number of data for which LSL > Xi
+NG
Number of data higher than the
upper specication limit value
Number of data for which USL < Xi
P Fraction defective P = ((-NG) + (+NG))/N
Cp Process capability index
Cp = TOL/(6σn-1)
TOL: USL − LSL
Cpk
When process capability index
bias is considered
Cpk = Zmin/3
Zmin: The lower value of Zusl and Zlsl
Zusl = (USL − X¯)/σn-1, Zlsl = (X¯ − LSL)/σn-1
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Calculation of MODE3
N: Number of sample data
MAX: Maximum data value
MIN: Minimum data value
n: Number of subgroups
A2: Refer to the conversion table below
D3: Refer to the conversion table below
D4: Refer to the conversion table below
* The maximum sample data number of the subgroup is 10.
Variable Table
Sample size n A2 D3 D4
2
3
4
5
6
7
8
9
10
1.880
1.023
0.729
0.577
0.483
0.419
0.373
0.337
0.308
0.076
0.136
0.184
0.223
3.267
2.574
2.282
2.114
2.004
1.924
1.864
1.816
1.777