Andy, Here is a toy example where such model might make sense. Suppose y is the total income of an individual over the last two years and x_1 and x_2 are the taxes he paid on each of the two years. If taxes were linear in income then y ~ a*(x_1 + x_2). With a progressive tax system it is y ~ f(x_1) + f(x_2)
Hope it makes more sense now, Vadim > -----Original Message----- > From: Liaw, Andy [mailto:[EMAIL PROTECTED]] > Sent: Wednesday, February 19, 2003 5:33 AM > > Vadim Ogranovich wrote: > > > > >Dear R-Users, > > > > > >I need to find a smooth function f() and coefficients a_i > > that give the best > > >fit to > > > > > >y ~ a_0 + a_1*f(x_1) + a_2*f(x_2) > > > > > The model is very strange (to me, at least). It's not > obvious to me that > it's even identifiable. (Sorry that I don't have anything > constructive to > add.) > > Andy -------------------------------------------------- DISCLAIMER \ This e-mail, and any attachments thereto, is intend ... [[dropped]] ______________________________________________ [EMAIL PROTECTED] mailing list http://www.stat.math.ethz.ch/mailman/listinfo/r-help
