Calculate the dispersion parameter for a quasi-poisson model

Converted from STATA from armstrong 2014 supplement with LLM guidance. Minimal error checking of these inputs at present.

Usage

calc_dispersion(y, X, beta, stratum_vector)

Arguments

y

a vector of outcomes

X

a matrix of predictors, typically the crossbasis output

beta

a vector of coefficients

stratum_vector

a vector describing the stratum