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11 STATISTICS TERMINOLOGY
Term
Meaning
COEF OF VARIAT’N
Coefficient of Variation. The standard deviation divided by the mean for a group
of readings, expressed as a percentage.
HIGHEST READING
The value of the maximum thickness in a group of readings.
LOWEST READING
The value of the minimum thickness in a group of readings.
MEAN
The average of a group of readings; the sum of the individual readings divided
by the number of readings.
NO. OF READINGS
Number of Readings. The running value for the number of readings taken in a
group. In the case of the mode, the Number of Readings is the number of
values recorded, not the total number of readings taken.
STD DEVIATION
Standard Deviation. A statistical measure of the spread of values in a group of
readings.
PERCENT GREATER
OR EQUAL TO NDFT
The percentage (%) of readings greater than or equal to the value of NDFT (see
“Set NDFT” on page 31)
PERCENT BETWEEN
90% AND 100% NDFT
The percentage (%) of readings less than the value of NDFT but greater than
90% of the value of NDFT.
90:10 PASS / FAIL
90/10 test results:
= pass,
= failed on 90% test,
= fail due to a reading
below 0.9xNDFT (if a number between 1 and 10 is displayed, insufficient
measurements have been taken to be statistically valid - take more measurements)
Op_456_3_English.book Page 38 Thursday, January 22, 2009 7:58 PM