On Fri, 12 Feb 2010, Allin Cottrell wrote:
 On Fri, 12 Feb 2010, Ignacio Diaz-Emparanza wrote:
 > With periodicity ($pd)> 1 (quarterly or monthly data,..)
 > y[1] is refering to the first observation of the series,
 > but with annual data it is refering to the observation of year '1'.
 Duh, sorry, I wasn't paying enough attention. I'll think about
 it... 
The difficulty is this: with quarterly or monthly data there's no
possible confusion between the alternate forms of identifying
observations: "obs=1975:4" versus "obs=3", for example. But with
annual data confusion is possible. But I'll consider it some more.
Allin