[R] Negative binomial parameterisation in mgcv

[Mark Payne]

Dear R-help,

The negative binomial distribution has several different
parameterisations, but I can't seem to figure out what the exact one
used in mgcv's negbin family is? negbin() requires a theta argument,
but its not clear anywhere in the documentation (that I can find), how
this parameter should be interpreted - for example, can it be less
than 1?

Best wishes,

MArk