Ziehm Imaging, Inc.
Vision Installation Manual
MAN 06-0015, Rev. A
Page 17
M a i n t e n a n c e R e p o r t : C h e c k R e p r o d u c i b i l i t y
Calculating the Coefficient C
For n individual measurements, the variation of the coefficient C is obtained from.
1. Calculate the average
Add the four dose values and divide the sum by four.
X1 + X2 + X3 + X4 = X (Average)
n
2. Calculate the difference
Subtract each measured value from the average.
X
i
- X =
∆
(Difference)
3. Calculate the difference squared
Multiply the difference by itself.
(X
i
- X)
2
=
∆
2
4. Calculate the square root
Add the sum of the four differences squared and divide by 3. Write the result below.
S =
5. Calculate the variation coefficient
Divide the sum (obtained in step 4) by the average value (obtained in step 1).
S
=
calculated standard deviation
X
=
average value of all individual measurements
X
i
=
measured value of the
i
th
measurement
n
=
number of individual measurements
∆
=
difference
∆
2
=
difference squared
Measurement
Radiation
Exposure
Average (X)
= Difference
Difference
Squared
Sum =
Sum divided by 3 =
