Hioki RM3542-50, Instruction Manual

Page: 90 / 234

6.3 Performing Statistical Calculations on Measurement Values
84
Statistical calculations can be performed and results displayed for up to 30,000 measurement val-
ues.
Printing is also available (p. 93).
Calculation types: average, maximum and minimum values, population standard deviation, sample
standard deviation, and process compatibility indices
Deleting Statistical Calculation Results
Stored data is automatically erased at the following timings:
6.3 Performing Statistical Calculations on
Measurement Values
Maximum X
max
= MAX ( x
1
, ....., x
n
) In these formulas, n represents the number of valid
data samples.
Hi and Lo are the upper and lower thresholds of the
comparator.
* The process capability index represents the quality
achievement capability created by a process, which
is the "Quality variation and width bias possessed
by the process".
Generally, depending on the values of Cp and CpK,
process capability is evaluated as follows:
Process capability
Cp, CpK > 1.33 ........................... Ideal
1.33
≥
Cp, CpK > 1.00 ................ Adequate
1.00 ≥ Cp, CpK ........................... Inadequate
Minimum
X
min
= MIN ( x
1
, ....., x
n
)
Mean
Population standard
deviation
Standard deviation
of sample
Process capability
index*
(variation)
Process capability
index*
(bias)
n
x
x

=
1
6
−
−
=
n
Lo Hi
Cp
σ
1
6
2
−
− + − −
=
n
x Lo Hi Lo Hi
CpK
σ
• When only one valid data sample exists, standard deviation of sample and process capability indices are
not displayed.
• When σ
n-1
= 0, Cp and Cpk are 99.99.
• The upper limit of Cp and CpK is 99.99. If Cp and CpK>are 99.99, the value 99.99 is displayed.
• Negative values of CpK are considered as CpK = 0.
• If statistical calculation is turned off and then back on without first clearing the calculation results, calcula-
tion resumes from the point when it was turned off.
• Measurement speed is reduced when statistical calculation is enabled.
• When Auto-Memory is enabled (ON), statistical calculation is forcibly enabled (ON).
• When statistical calculation is disabled (OFF), Auto-Memory is forcibly disabled (OFF).
•
When the memory function setting (including data-mem-
ory) is changed (p. 156)
•
When the range is changed (p. 32)
•
When changing comparator settings (p. 36)
•
When printing the statistical calculations (p. 93)
•
When the measuring object is changed (p. 28)
•
Upon system reset (p. 75)
•
Upon setting the auto-memory number of values to store
(p. 82)