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Industrial Statistics with Minitab by Xavier Tort-Martorell Llabres, Lluis Marco Almagro, Pere Grima Cintas

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22.3 Simple Regression with ‘Fitted Line Plot’

Stat > Regression > Fitted Line Plot

nc22uf010.eps
nc22uf011.eps

The goodness of fit indicators that appear in the upper-right box of the scatterplot are:

S: Standard deviation of residuals (residual = true value of the response variable − fitted value obtained using the equation)
R-Sq Coefficient of determination (R2): Measure of the goodness of fit. It is computed as the square of the correlation coefficient (×100, to be given in %)
R-Sq (adj): Adjusted coefficient of determination. Measure of the goodness of fit used in multiple regression (does not apply in simple regression).

The session window only adds the analysis of variance table, which can be used as a significance test for the coefficient of the explanatory variable. In our example, the coefficient of the height variable is clearly significant since the p-value = 0.000.

22.3.1 Logarithmic Transformation of Data (Using ‘Options’)

nc22uf012.eps

Sometimes, a much better model can be obtained using a logarithmic transformation of the values of X and/or Y. An example of a remarkable model improvement is obtained ...

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