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Published byJeff Slagter Modified about 1 year ago

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Bivariate Data Pt. 4 October 2011

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Gotchas Don’t fit a straight line to a nonlinear relationship. Use residual plots to determine if the linear fit is acceptable. Beware of extraordinary and unusual points, but never change the data to make it fit. – Errors can be made in data collection, but they should not be “fixed” by the statistician. Don’t extrapolate beyond the data. The assumptions that are in place for a linear model do not necessarily extend beyond the given predictor values.

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More gotchas Do not assume that the predictor causes the response just because the linear model is good. Never choose a model based on R 2 alone. Always check the residual plot for additional info.

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