[R] Interesting behavior of lm() with small, problematic data sets

S Ellison S.Ellison at LGCGroup.com
Wed Sep 6 15:10:30 CEST 2017

> I think what you're seeing is
> https://en.wikipedia.org/wiki/Loss_of_significance.

All the results in the OP's summary are reflections of finite precision in the analytically exact solution, leading to residuals smaller than the double precision limit. The summary is correctly warning that it's all potentially nonsense, and indeed the only things you can trust are the coefficient values (to within .Machine$double.eps or thereabouts)

Interestingly, though, my current version of R (3.4.0) gives numerically exact coefficients (c(1,0) and identically zero standard errors.

So this particular example is apparently version-specific.

S Ellison

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