Exercise

Model selection

You have applied two Negative Binomial GLMs; one, neg_binom_glm, includes all of the terms, while the other, neg_binom_glm_small, excludes the interaction between stream_flow and time. Now it's time to decide which model to use to help answer the research question.

Note that the dragonflies data set, neg_binom_glm and neg_binom_glm_small models, custom dispersion() function, and ggplot2 and MASS libraries have been preloaded.

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Calculate the dispersion for each model.