Re: [Gretl-users] GUI points

Am 12.11.2016 um 23:12 schrieb Allin Cottrell: > Hmm, I guess so. Maybe worth noting that Belsley's condition number > calculation involves scaling but not centering. So try the following: > > <hansl> > open hall.gdt > series c10 = consrat * 10 > series cc = consrat - mean(consrat) > eval cnumber({const, ewr, consrat}) > eval cnumber({const, ewr, c10}) > eval cnumber({const, ewr, cc}) > </hansl> > > Multiplying consrat by 10 makes no difference to the condition number, > as you say. But centering it reduces the value a great deal. (With > correlation, of course, neither scaling not centering makes any > difference.) (And centering ewr, too, then leads to cnumber values below 2, BTW.) I haven't looked (or wasn't forced to look) at these concepts in the past, but this behavior of the condition number I find odd. It feels as if it makes only sense if the data are demeaned. And including a constant term in the variable set for the calculation of cnumber obviously doesn't do the same thing.