nested models in nls

["Steve Roberts" <steve.roberts@man.ac.uk>]

Greetings,

Quick question: Does anyone know any nice trick for specifying a 
nested model in nls. Obviously I can create the indicator variables 
by hand, but it's messy. Any clever tricks?

Thanks,

Steve.


  Dr Steve Roberts 
  steve.roberts@man.ac.uk
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| Senior Lecturer in Medical Statistics,      | Health Services Research Unit,  
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| Biostatistics Group,                        | Central Manchester and 
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