Check for zero-inflation in count models
check_zeroinflation() checks whether count models are
over- or underfitting zeros in the outcome.
check_zeroinflation(x, tolerance = 0.05)
x |
Fitted model of class |
tolerance |
The tolerance for the ratio of observed and predicted
zeros to considered as over- or underfitting zeros. A ratio
between 1 +/- |
If the amount of observed zeros is larger than the amount of predicted zeros, the model is underfitting zeros, which indicates a zero-inflation in the data. In such cases, it is recommended to use negative binomial or zero-inflated models.
A list with information about the amount of predicted and observed zeros in the outcome, as well as the ratio between these two values.
if (require("glmmTMB")) {
data(Salamanders)
m <- glm(count ~ spp + mined, family = poisson, data = Salamanders)
check_zeroinflation(m)
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