Ultrospec 2100 pro User Manual

Least squares regression analysis and linearity
The slope (or best straight line) and intercept in a kinetics assay or standard curve
determination is calculated from a least squares linear regression of the data. The
following equations are used, where n is the number of data points:
Slope
=
∑
∑
∑ ∑
∑ ∑
x y−n xy
x x−n 2
x
( )
∑ ∑ * /
Intercept = y − x slope n
Linearity is an estimate of the “goodness of fit” of the least squares linear
regression analysis, a perfect fit being 100%. It is used in both the Reaction Rate
and Standard Curve modes, and is expressed by a coefficient of determination (r 2 ),
calculated using the following equation:
Quality
= 100*
∑ x∑
y − n∑
2
2
( ∑ x)
− n∑
x )( ∑ y)
2
2
( − n y )
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26 Ultrospec 2100 pro, English Issue 06 - 12/2003
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