Calculation Of Mean; Calculation Of Standard Deviation (<5 Replicate Analyses) - Hach AutoCAT 9000 Instruction Manual

5.2.4.1 Calculation of Mean

5.2.4.2 Calculation of Standard Deviation (<5 replicate analyses)
5.2.4.3 Calculation of Standard Deviation (>5 replicate analyses)
50081_AutomatedTitration.fm
The mean is calculated using the following equation:
N
∑
R
i
i 1
=
Mean ---------------- -
=
N
Where:
th
R is the result from the i replicate measurement (i.e., Test)
i
N is the number of replicate measurements.
When the number of replicate measurements is between 2 and 5, the standard deviation
of the mean, S is estimated using the following formula:
Mean
R R
–
⎛ max min ⎞
---------------------------------
⎝ ⎠
Q
S ----------------------------------------- -
=
Mean
N
Where:
R is the maximum value obtained from the replicate measurements
max
R is the minimum value obtained from the replicate measurements
min
is taken from the following table:
Q
If more than five replicate measurements (i.e., Tests) are made, the standard deviation of
the mean, S is calculated using the following formula:
Mean
N
∑
N R
2
∑
R
i
–
i 1
=
------------------ -
N
i 1
=
S
------------------------------------------- -
=
Mean
( )N
N 1
–
The final average is reported as: Mean (± S
Collecting and Accessing Data
2
N Q
2 1.128
3 1.693
4 2.059
5 2.326
2
i
)
Mean
Collecting and Accessing Data
Page 47