Hi Roger (and Barry),

> Maybe just do it in the usual way, repeating the i and j specific
variables?
> Unless you want to constrain anything, it shouldn't be more than reshaping
> to long format and rep()'ing the origin and destination variables, should
> it? Maybe provide a link to data and output using other approaches?

You are absolutely right Roger. In addition, I also failed to properly
specify my constraints.
For anyone out there who might be trying to do something similar, using a
data.frame in long format (as suggested by Roger and Barry Rowlingson), the
proper specification for the production constrained model mentioned in the
original question is:

> glm(flows ~ 0 + prodconst + log(pop) + log(dists), data=my.data,
family=poisson)

This is based on using the following data example where 'pop' and 'dpop' are
the origin and destination populations (or any other measure of attraction),
and 'attrconst' and 'prodconst' are constraint factors for attraction- and
production-constrained models respectively. My terminology might be off
here, but you get the idea!

> my.data
    flows dists      pop     dpop prodconst attrconst
1       0     0 11848000 11848000        1         1
2  283049   219 11848000 37056000        2         1
3   87267  1009 11848000 40266000        3         1
4   29877  1514 11848000 16327000        4         1
5  130830   974 11848000 29920000        5         1
6   21434  1268 11848000 13096000        6         1
7   30287  1795 11848000 19025000        7         1
8   21450  2420 11848000  8289000        8         1
9   72114  3174 11848000 25476000        9         1
10 180048   219 37056000 11848000        1         2
11      0     0 37056000 37056000        2         2
12 237229   831 37056000 40266000        3         2
13  60681  1336 37056000 16327000        4         2
14 382565   755 37056000 29920000        5         2
15  53772  1049 37056000 13096000        6         2
...

Cheers,

Carson

-- 
Carson J. Q. Farmer
ISSP Doctoral Fellow
National Centre for Geocomputation
National University of Ireland, Maynooth,
http://www.carsonfarmer.com/

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