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Regression Line

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A best fitting line,

$\displaystyle p(t) = u + vt\, , $

to a set of points $ (t_i,f_i)$, $ i=1,\ldots,n$, can be determined by minimizing the sum of the squares of the errors

$\displaystyle \sum_{i=1}^n (f_i - p(t_i))^2\, . $

\includegraphics[width=.7\moimagesize]{a_ausgleichsgerade}

If we have at least two different $ t$-coordinates, we obtain the following formulas for the axis intercept $ u$ and the slope $ v$:

$\displaystyle u$ $\displaystyle = \frac{(\sum t_i^2)(\sum f_i)-(\sum t_i)(\sum t_if_i)} {n(\sum t_i^2)-(\sum t_i)^2}$    
$\displaystyle v$ $\displaystyle =\frac{n(\sum t_i f_i)-(\sum t_i)(\sum f_i)} {n(\sum t_i^2)-(\sum t_i)^2}\, .$    

see also:

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  automatically generated 3/20/2007