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Mathematics-Online lexicon:

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