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Exploring the Goodness of Fit in Linear Models - Is the Trend Changing?

Author(s): 
Scott A. Sinex

Could it be that your linear model is breaking down? Some linear models do not hold at high x-values. You can see how some calibration curves in chemistry start to develop curvature at high concentrations by using the Beer’s Law Simulator (click on the “Bad Cal” tab). Points at higher concentrations might appear to be outliers.

Another example illustrating emerging curvature is the "lightweighting" of the aluminum can, as shown in Figure 14. The possible future mass of the can is shown in Figure 15.


Figure 14. Aluminum can lightweighting (mass as a function of time)
Source: The Aluminum Association


Figure 15. Another possible conclusion from the same data

Scott A. Sinex, "Exploring the Goodness of Fit in Linear Models - Is the Trend Changing?," Loci (March 2005)

JOMA

Journal of Online Mathematics and its Applications

Dummy View - NOT TO BE DELETED