Micromeritics ASAP 2460, Operator'S Manual

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ASAP 2460 Operator’s Manual Appendix C
246-42800-01 - Aug 2013 C-45
SPC Report Variables
Regression Chart Variables
The line of best fit for the Regression Chart is calculated by the usual Least Squares method. (Refer to
BASIC Scientific Subroutines Vol II , by F.R. Ruckdeschel, Copyright 1981 BYTE Publications/
McGraw Hill, p. 16.) If there is only a single point or all N points have the same x-value, there can be
no line of best fit in the standard form.
Slope =
The coefficient of Correlation for this line is also calculated in the usual way. (Refer to Mathematical
Handbook for Scientists and Engineers , by Granino A. Korn and Theresa M. Korn, Copyright 1961,
1968 McGraw Hill, Sec. 18.4.)
Correlation Coefficient =
X

x
i
N
---------
=
Y

y
i
N
---------
=

x
i
X –
 
y
i
Y –
 

x
i
X –
 
2
-------------------------------------------

x

x
i
X –
 
2
N
-------------------------- =

y

y
i
Y –
 
2
N
-------------------------- =
Cov x y
  

x
i
X –
 
y
i
Y –
 
N
-------------------------------------------
=
Cov x y
  

x

y
-----------------------