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votes
1answer
51 views

Zero-inflated model predicting only a small range of values. I need help

I built a ZI model and it is producing predicted values that are from a very small range when compared to the observed values. Plus it does not produce any zeros. See the fitted vs. observed graph ...
2
votes
2answers
75 views

How do we compare count models for prediction and inference?

I have estimated a number of count models on a data, including Poisson, Zero-Inflated Poisson (ZIP), mixed-effects Poisson, mixed-effects ZIP and, a few different versions of each of these based on ...
5
votes
1answer
9k views

Fitting a model to a variable with many zeros and few but large values in right tail [duplicate]

I would like to fit a model to a dependent variable distributed like the one below (see picture). The distribution is a count of people (with specific characteristics) in various districts. This ...
1
vote
0answers
160 views

Predicted values in negative binomial model with 0-inflation

My count data are zero-inflated, for which I utilized glmmADMB. ...
1
vote
1answer
4k views

Hurdle model results interpretation and plotting

I am trying to determine the habitat of a species of dolphin. My data is highly zero-inflated, so I chose hurdle and zero-inflated negative binomial models to analyze it. I used the pscl package in R ...
1
vote
1answer
1k views

Prediction from Zero Inflated Models?

I have fitted a two stage generalized additive model to zero inflated data ("hurdle model"). I am modeling fishery spatial data (catch rates) as a function of different environmental variables (...
14
votes
3answers
4k views

Can a model for non-negative data with clumping at zeros (Tweedie GLM, zero-inflated GLM, etc.) predict exact zeros?

A Tweedie distribution can model skewed data with a point mass at zero when the parameter $p$ (exponent in the mean-variance relationship) is between 1 and 2. Similarly a zero-inflated (whether ...
5
votes
2answers
6k views

Modelling zero-inflated proportion data in R using GAMLSS

I am new to the gamlss package and would like to check that I am using the correct family for proportion data (tree species cover after treatment), which is bounded ...