CG204-EU-EN V2.1 3/11
11
n
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x
/
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Statistical Analysis Considerations
The meter calculates statistics from a maximum of 80 readings (For Group 1 through
Group 4, a maximum of 400 readings can be stored). Note that readings cannot be stored
when in DIRECT mode. However, statistics on these readings can still be calculated.
When the meter is powered off or if the working mode is changed (in the programming
menu), the DIRECT mode statistics will be lost. The following statistical values can be
calculated:
•
NO.: Number of readings
•
AVG: Average value
•
Sdev. : Standard deviation (square root of a data set’s variance)
•
MAX: Maximum reading
•
MIN: Minimum reading
Statistical Terms
Average value (
x
) is the sum of readings divided by the number of readings.
Standard Deviation (Sdev)
The sample standard deviation is a statistic that measures how the sample value is
distributed around the sample mean. The standard deviation of a set of numbers is the
root mean square of the variance S
2
The variance of a list is the square of the standard deviation of the list, that is, the
average of the squares of the deviations of the numbers in the list from their mean
divided by the(number of readings -1 )
Variance: S
2
=
)
1
/(
)
(
2
−
−
∑
n
x
x
Standard deviation: S=
2
S
NOTE:
Use the DELETE parameter from the programming menu immediately after an outlier
or erratic reading has been taken. Refer to the Delete function in Programming Menu.
Storage Capacity Overflow
In GROUP mode, if the storage capacity is exceeded, statistics will not be updated,
although measurements can still be made. If the memory is full, subsequent readings
will not be included in the statistics. The meter’s display will show “FULL” (in the
SINGLE measurement mode).
In DIRECT mode, when the memory is full, the newest reading will replace the oldest
reading and the statistics will be updated.
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