On Wed, 24 Feb 2010, Caro Landry wrote:
 I haven't found any answer to this problem online, and so am
hoping that
 someone can help me here.
 I need to:
 a) create a new series that comprises only the positive observation of a
 series
 b) only use the observations for which the new series are not equal to 0 in
 a NLS 
If the series is called "y":
smpl y > 0 --restrict
nls ...
Allin Cottrell