# Questions tagged [zero-inflation]

Excessive 0's in a variable compared to a specified reference distribution. Regression approaches include zero-inflated models and hurdle (2-part) models. For count data, zero-inflated and hurdle models based on Poisson or negative binomial distributions are common (ZIP/ZINB and HP/HNB).

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### Estimate π of zero inflated Poisson

Can anyone show how to estimated the π of the zero-inflated-Poisson? f(y)=π+(1−π)e^(−λ), if y=0; =(1−π)λ^ye^(−λ)/y!, if y=1,2.... where π is the probability that the observation is ...
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### How to handle 0 inflated data set?

How to handle a data set with high number of 0's. I am trying to predict automobile insurance claims of people. So many of them of are zeros. If the claim == 1 ...
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### Zero inflated negative binomial in Stata

I'm trying to fit a negative binomial model on overdispersed count data with a large number of zeros. I have two questions: 1) How do I know that I have an 'excess' number of zeros, and that I should ...
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### Zero inflated data. ordinal variable prediction. Insurance data

I have an insurance claims data with claim amount as a target variable. The claim amount has a lot of 0s . The output is to predict the high-risk customers. i.e., to preserve the order of claim ...
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### variance-covariance matrix of a “zeroinfl” object [closed]

There is a command in R to derive the variance-covariance matrix of a glm (model) objects. Does any one know if there is a command which one can derive variance-covariance matrix of a Zero inflated ...
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### Appropriate Model for inflated variable at non zero value

I have a question regarding the appropriate regression model for a continuous variable that ranges from zero to 10. This variable has a large concentration of observations in the "10" value (almost 50 ...
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### random effect required?

For my Bachelor-Thesis i want to model the international stocks of migrants from country $i$ staying in country $j$ in year $t$ in dependency of the minimal geographic distance between $i$ and $j$, ...
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### Predicting future values with hurdle Poisson model

I executed a hurdle Poisson model on test dataset that contains one y (dependent variable) and one x (independent variable). ...
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### Linear Regression with both count and continuous zero inflated variables

I am trying to produce a multivariate linear regression model to predict the value of a continuous variable. I have lots of variables with potential explanatory power, some are binary (e.g. sex), ...
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### What do the outputs of my zero inflated poisson model mean?

I am looking a counts of fish within different size classes (0-10, 10-20 etc) between 3 different reef sites, 3 different depths and 2 different survey methods. However, naturally on all observations ...
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### Zero-inflated GLMM: correct use of AIC and comparing levels of fixed factor

I am struggling with a ZIGLMM in R. I have a data set on freshwater plant propagules (response variable) and the relation with the ecological state of ponds. Pond state is a categorical factor with ...
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### Are a zero-truncated Poisson and basic Poisson nested or non-nested?

I've seen plenty that discusses whether a basic Poisson regression is a nested version of a zero-inflated Poisson regression. For instance this site argues that it is, since the latter includes extra ...
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### Dealing with imbalanced/zero-inflated training examples for regression

I am trying to predict the rainfall in a desert with a regression model. However, as you might expect, most of my training examples have zeroed labels. I have two questions: a. What is an appropriate ...
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### Regression with zero-inflated continuous variable, zero-inflated binomial variable and integer response variable

Consider a model where: Y (response variable): continuous and both positive and negative X1 (explanatory variable): continuous data, but with many zero values X2 (explanatory variable): binomially ...
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### Poisson regression, hurdle models, and zero-truncated models

My dataset (with the dependent variable being a count variable) has two features that are different from a standard Poisson regression. I haven't been able to find a more advanced model that accounts ...
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### SEM with zero-inflated indicators

I am using SEM and my measurement model includes around 15 items that are all rated on a 0-10 scale but highly skewed towards zero. I am wondering whether there is a way to estimate the measurement ...
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### How to interpret coefficient estimate from a zero inflation model?

gling with the interpretation of the coefficients of a zero-inflation model and I find no clear answer in the net. Maybe someone can help me and other people in the same situation. After fitting ...
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### Comparing two distributions with zeros (X=ordinal, Y=count)

I am more or less familiar with the stats. However, recently I ran in the following problem. Problem: I would like to compare two distributions that are zero inflated (to some extend). The two distr. ...
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### Testing for difference in group means with skewed data with many zeros

Background I am trying to perform a test for difference in means between two groups in a dataset with around 25k records, where 97% of the Y values are 0, and the non-zero Y values are heavily skewed,...
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### Computational error running regression model

This problem has held me up for three days now, so I really hope somebody here has a solution for the problem. I have a model with an excessive number of zeros, so I use a zero-inflated poisson ...
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### Zero-inflated model: non-finite value supplied by optim

So I have the following model predicting the presence of an animal on a certain spot. As a time unit quarter is initially used, but for one of the species of animals there is some (little) interesting ...
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### How to Test for Some Basic Assumptions of (Zero Inflated) Negative Binomial?

I am currently working with a T dominant panel --time-series cross-section dataset-- that has N = 8 (eight European countries) and T = 28 (28 quarters for each country). The dependent variable --...
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### Which test can I use to compare two count data means with a lot of zeros?

Suppose I have two count datasets, lets say the count of tigers across different years at two places. Now for most of the years we have 0 tiger sightings. For eg. ...
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### Predicted values in negative binomial model with 0-inflation

My count data are zero-inflated, for which I utilized glmmADMB. ...
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### Revenue based AB test

I have preformed an AB test on revenues (as my target is to increase revenues). Two groups of users were offered with a different marketing offer which in group A (Blue) led to a higher conversion ...
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### Chosing the right test for weekly disease counts

I am using STATA to analyze count data (weekly disease counts), and I am trying to pick the best test between Poisson, negative binomial and zero-inflated Poisson / negative binomial but I am not sure ...
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### Sensitivity analysis on constants: logit transformation for ANOVA

I have categorical looking-time data (looks to visually presented items A, B, C and D over a number of seconds), containing 0s and 1s. I want to compare groups (adults, children; n=~30 for each group) ...
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### Comparing count data models?

I am trying to fit Negative binomial, Zero Inflated Negative Binomial, Negative Binomial Hurdle, and Random effects negative binomial. Here is the value of AIC for different model: Negative Binomial: ...
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### 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 ...
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### How to improve the fit of a zero-inflated, negative binomial glmmADMB model

I have been trying to fit count data that is zero-inflated and overdispersed using generalized linear mixed models. My research led me to the glmmadmb function in ...
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### Gibbs sampling deriving complete conditionals with mixture priors

My question is about the derivation of the complete conditionals for Gibbs sampling in a hierarchical model where some of the parameters are mixtures of point-masses and Normal distributions. The ...
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### How to calculate variance contribution in a Zero-Inflated Poisson regression?

I was wondering if anyone has an idea on how to calculate the contribution to variance of each independent variable in a Zero-Inflated Poisson. How would it even work if you actually have two models ...
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### Double Hurdle model with continuous DV and two sources of zeros

I want to regress a data set that contains a lot of zero's (~55%) and is determined by a typical 2-stage decision process generating the zeros: Consumer decides to apply for a bank loan or not (0-1) ...
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### Comparing results from reference coding and orthogonal coding in a linear model?

The problem: I'm trying to fit a zero-inflated negative binomial model to count data (catches of larval fish). I have three factors, and an offset variable, which is the volume of water filtered by ...
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### Help with zero-inflated generalized linear mixed models with random factor in R

My study has a complicated design and I am not sure if I am modeling my zero-inflated data correctly. I have seed abundances and seedling abundances for 11 species. I have one main "treatment" with ...
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### zero-inflated negative binomial in Stata

I am trying to run a zero-inflated negative binomial analysis in Stata (zinb). My question/problem is this: the model's convergence seems dependent on which and how ...
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### Calculating OR and IRR for a zero-inflated negative binomial model from estimates

I used the PSCL package to run a zero-inflated negative binomial model on some count data I have. This package gives the following output: for the zero part of the model: ...
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### What is effect on PCA of having too many zeros in the data?

I want to use Principal Components Analysis to derive dietary patterns. However, my data have many zeros (no intakes) for many observations. I'm unable to find relevant literature to know how biased ...
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### Simulate from a zero-inflated poisson distribution

I am trying to simulate from observed data that I have fit to a zero-inflated poisson regression model. I fit the data in R using zeroinfl() from the package pscl, but I am having trouble figuring out ...
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### How to model non-negative zero-inflated continuous data?

I'm currently trying to apply a linear model (family = gaussian) to an indicator of biodiversity that cannot take values lower than zero, is zero-inflated and is ...