## Sum of residuals ~ ε [Design Issues]

» I disagree. In the model ε = 0. However in the fit, the sum of residuals is only asymptotically 0. We shouldn’t speak of bias when we obtain something sufficiently close to the numeric resolution of the machine.

Hi Helmut!

I don't mean that we have bias because 0 not equal eps(). Numericaly we can make calculation with values lower that eps() like: (1E-40 + 2E-40) * 3E+40 = 9.0. Problems can start with things like this: 1 + 1E-40, for example: (1E+40 - 1E+40 + 1 == 1E+40 + 1  - 1E+40) == false. - this not what about a try to say.

I try to say, that zero residual (or effective zero residual) can't be at all, "by definition" in linear model.