Mitutoyo DP-1VA LOGGER - Page 41

25
2 Basic Operations
No. 99MAM029A
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Statistical calculation values
Printout 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