Whoops…I did it again…
…and forgot that R-squared statistics are weird in R when the intercept is removed. There’s so much about this issue, so you really don’t have to read on. This post really is me just underlining one of my common silly mistakes so that I don’t ever redo it. This FAQ says it all. I understand these arguments, but the problem for me is that in interactive mode I often centre the response variable before sending it to
lm and then automatically add the
-1 to the formula. But in my head I know there’s still an intercept. For some reason I can remember to mentally subtract a degree of freedom from the ANOVA tables but I always forget about the R-squared. I think the solution is just to never use
-1 if I don’t really mean it.