Computes the overdispersion parameter \(w=1+\mu/\theta\) for a negative
binomial distribution parametrized by its expected value \(\mu\) and with
variance \(\mu+\mu^2/\theta\). The overdispersion is added as a new column
to the input data.table, meaning that this function modifies
its input.
negbin_overdispersion(table)A data.table with columns mu, theta and possibly
others.
The same table, with a new column overdispersion.