[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]
Re: st: Nonlinear regression and constraints
At 09:04 PM 6/28/2005 -0700, Daniel Schneider wrote:
Even if -nl- allowed the constraints option, I don't think these would be
legal constraints; as far as I know, you can't use something like >=, you
can only use =.
constraint define 1 X1MX1SQDIVX3 >= 0
constraint define 2 X2SQMX2DIVX3 >= 0
constraint define 3 X1MX1SQDIVX3 <= 1
constraint define 4 X2SQMX2DIVX3 <= 1
Unfortunately, constraints() seems not to work with -nl-?
Is there any other way to to do the constraints with -nl-?
Also, my impression is that -nl- doesn't need the constraints option
because constraints can be specified using the -nl- command itself.
I'd be curious to know if there is some direct way to specify a range of
values for the constraint, like you want; as far as I know, there always
has to be some sort of equality statement.
Is there some way to transform the equation, so that, say, you wind up
taking the inverse logit of the parameters of the transformed equation to
get back to the parameters of the original equation? The inverse logit of
any number will always range between 0 and 1. You'll see programs do
little tricks like estimate the log of a parameter when the parameter
itself needs to be positive.
Richard Williams, Notre Dame Dept of Sociology
OFFICE: (574)631-6668, (574)631-6463
WWW (personal): http://www.nd.edu/~rwilliam
WWW (department): http://www.nd.edu/~soc
* For searches and help try: