Hello Achim, > Not quite. Consult your statistics textbook for the correct interpretation > of p-values. Under the null hypothesis of a true intercept of zero, it is > very likely to observe an intercept as large as 13.52 or larger. thank you for that help. I suppose the net doesn't have a detailed explanation of the output of summary.lm for someone with very little knowledge about statistics? I worked through J. Verzani "simple R" but it does assume some pre-knowledge.
> > So I repeat the regression forcing the intercept to zero: > > Do you have a good interpretation for that? In this case, my knowledge of the physical reality behind the numbers tells me that the intercept should be zero. > The model without intercept needs to be interpreted differently. The > p-value pertains to a regression with intercept zero and slope 0.292 > against a model with both intercept zero and slope zero. In other words, of course the slope of 0.292 is almost infinitely better than a zero slope? But the same would be true for most slopes >0, I suppose. So what is the correct way to compare the quality of the regression with and without intercept? Assuming that I don't know from the physical reality that the intercept should be zero, what can I say to support one model against the other? Thanks, Jan ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.