does gls have the corstr object can you fit negbin what is the correlation mechanism in negbin glm how to re-run negbin how to fit negbin glm how to fit a negbin glm what is negbin's correlation structure can negbin glm be combined with gls how can you find correlation in negbin glm what is the arg structure for negbin negbin glm correlation structure how to use negbin glm in glm which glm model does not include an autoregressive correlation structure? how to fit a negbin glm with a polynomial correlation analysis why is negbin glm not corregressive what is the corstruct of negbin why does negbin glm use corstr which correlation structure does the negbin glm use which model uses a negbin correlation why is it important to fit a negbin glm model