# 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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### What is the best method to determine significance in a zero-inflated poisson model?

I am currently trying to run a zero inflated mixed effects model in R using the package glmmTMB following a significant test of zero-inflation (using the function testZeroInflation() in the package ...
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### Modelling zero-inflated percentage data (vegetation cover) from single predictor variable

I am quite new to regression in R. I would like to analyse the relationship between 'Vegetation Cover'(response variable) and a single predictor variable 'Canopy Openness'. 'Vegetation Cover' is a ...
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### Formula of a zero-inflated negativ binomial with link to probit

I'm looking for the right notation of the probit linkfunktion in a zero-inflated negative binomial. g is the negative binomial and π the link function. Thank you very much!
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### GLMM hurdle model for continuous data -Truncated negative binomial family in glmmTMB?

I am running a hurdle model using the glmmTMB function. My dependent variable is continuous and >= 0. I was looking for a function that would allow me to model the binary response in a logistic ...
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### How can I compare two zero inflated continuous datasets?

I have two zero-inflated datasets such as, dt1= 0, 0.1, 0.125, 0, 0, 1.25... dt2= 1.01, 0, 0, 0.25, 0,... I want to check the differences, like t.test for ...
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### Zero inflated continuous outcome variables

I am trying to model a continuous outcome variable(non-integer, with excess zeros) by two independent variables. I have seen that people have referred to the compound poisson gamma model( https://doi....
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### How can we put in firm & time fixed effects in zero inflated count model in R?

I am running a zero-inflated count data model where my dependent variable is a count variable and my independent variable is a continuous variable. Since I have plenty of structural zeros in my data, ...
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### How to interpret GLMM results?

My question is related with my previous post Extract variance of the fixed effect in a glmm. However, in this case I change the model that the GLMM follow. It follows a log family and as there are ...
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### Zero-inflated negative binomial regression on gut microbiome data in R

thank you guys so much in advance! I got a table, containing the information of gut microbial composition of different groups, that is, the count data of different bacteria in each sample of different ...
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### Are empirically derived composite scores influenced by “zero inflation”?

I am helping a friend analyze a set of self-report ethological data. The aim of the data is to determine whether certain guinea pig pairings (dyads/triads - 2 males, 2 females, 1 male+2 female, etc.) ...
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### Need help understanding hurdle model specification and results interpretation

I am trying to use hurdle gamma model for one of my use cases, to handle a zero-inflated scenario. I have a very simple code creating dummy data with quite a few zeros. ...
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### How to deal with zero inflated columns in dataset?

I have a dataset on which I am trying to fit a Linear Regression model. It has 4 independent variables. I am trying to predict my dependent variable using these four columns. However, 2 out of these 4 ...
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### How to know whether a zero-inflated model is the way to go? Both poisson and negative binomial do not fit my count data

I have a dataset with count data as response variable ranging from 0-5 (number of chicks fledged). I intend to carry out a GLMM and need to know which distribution my data follows. I used the descdist(...
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### Comparing a hurdle model with a “direct” model

I am building xgboost models for prediction of insurance risk, the risk being assumed to follow a tweedie distribution with tweedie variance power between 1 and 2 (https://en.wikipedia.org/wiki/...
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### Choosing a model for zero-inflated self-reported spending outcome

My outcome variable is individual's self-reported spending (\$), which is distributed as follows (rounded to integers). I want to add several independent variables to examine their relationships, and I ...
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### How to identify which variables are collinear in a singular regression matrix? [duplicate]

I have a matrix on which I am performing a zero inflated regression model but it return an error indicating collinearity between some of the variables ...
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### Warining “system is computationally singular: reciprocal condition number = 1.49911e-34FALSE” when running zeroinfl() [duplicate]

I am using the pscl package to run a zero inflated estimation, however when I do I get the following warning: ...
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### Help with computing confidence intervals for zero-hurdle model

I am trying to calculate confidence intervals for the exponentiated coefficients of a hurdle model. I know I can't use the confint function as with normal GLMs, and suspect I have to use some kind of ...
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### Zero-Inflated Negative Binomial models for panel data

Is there any implementation of Zero-Inflated Negative Binomial models for panel data? So far I've checked out the usual suspects in terms of R packages, but as far as I can tell neither ...
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### How to get p-values for the zero-inflated part of a model?

I am having a problem that I am not finding an answer anywhere online. I used glmmTMB to fit a mixed-model. My data is zero-inflated and I am including 3 variables in the zero-inflated formula. I was ...
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### Zero-inflated generalized Poisson mixed effect model with glmmTMB still zero inflated

I am trying to analyze a dataset using number of flowers as response variable and the interaction between two treatment variables (categorical with 2 and 3 levels) as covariates. I also have a random ...
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### Rational procedure of fitting GLM zero-inflated model and potential pitfalls

I would like to ask if the following way of thinking is valid. Some context first, we have a response variable which is count and a few other explanatory variables and also one random effect variable. ...
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### Would it be appropriate to use Cohen's ds to evaluate the effect size in a negative binomial model?

I am working on a research project that involves the use of a zero-inflated negative binomial model. In the model I have included the interaction term between a binary and continuous predictor. The ...
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### What is the direct consequence of excess zeros/inflated data?

In many books and articles I've read that in a presence of many zeros in count data (correct measurement, for example "0 sales on Tuesday") we should go for hurdle or zero-inflated models. I'm ...
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### interpreting residual plots for zero-inflated linear mixed model

I am modelling a behavioural response (i.e., # times behaviour was observed/time observed [no longer an integer value]) in relation to disturbance levels (continuous) and the health status of the ...
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### Model effect test for zero-inflated poison regression with a three-level categorical predictor

I have a question about the model effect test for a zero-inflated Poisson regression I conducted a zero-inflated Poisson regression with a continuous dependent variable (Credit) and a 3-level ...
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### Tobit model for continuous zero inflated data?

I would like advice on how to apply an appropriate linear model to my data. I have several continuous independent variables, and a dependant variable with continuous distance measurements. This ...
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### What model for continuous data with excess zeros?

I am relatively new to statistics and have an issue with choosing an appropriate model to describe my data. I am looking at geographical distribution of point occurrences of a species. As a measure ...
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### Logistic regression segmentation performance

A data set contains observations belonging to these possible categories. Group 1: observations with indicator 1 Group 2: observations with indicator 0 that similar to observations in group 1 Group 3: ...
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### Decision boundary for logistic regression in Hurdle (two-part) GLM

I am reading . The authors use a two-part generalized linear model to detect differentially expressed genes in single-cell RNASeq data. Context Single-cell RNASeq is a technique for detecting ...
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### strange outcome in Poisson regression in SAS of dataset with excess zero

figure 1 shows the distribution of the number of event which indicates excess zero(the proportion is 98.98%),and the mean of outcome variable is much lower than its variance(mean=0.0246693,var=0....
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### zero inflated model in R, building the model with pscl, not understanding use of ' | 1'

I have count data with lots of zero. I have done a GLM with poisson distribution, and I think that using the zero inflated model might improve the fit. Now my problem, I have been working with SPSS. ...
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### Dealing with zeros in the dependent variable generated by separate processes

There are several questions here on dealing with zero inflated dependent variables, but my question is slightly different than them. I am working with a continuous/count dependent variable. The ...
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### Statistical analysis. Help fitting 2 stage or hurdle model on Zero inflated semi-continuous data

Here is a link to My data drive.google.com/open?id=1rDEciVwTVWs3TlVV_hi4WNalEt6cjVHY I'm trying to model cpue (response variable) and tell whether any of the explanatory variables have a significant ...
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### Trouble getting hurdle model to converge for continuous zero inflated data

I'm trying to fit a generalized mixed effect model for zero inflated semi-continuous data in R using the GLMMadaptive package. I have 13 variables but even just ...
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### Large standard error of intercept and low overdispersion parameter from negative binomial hurdle model using glmmTMB

I am running hurdle models on some count data using the R package glmmTMB. For one of my models, I tried the "truncated_nbinom1" family, but this model fails to converge. When I use the family "...
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### Is there an equation for the median and percentile of a zero-inflated Poisson?

This question gives answer to the mean and variance of the zero inflated Poisson distribution, but is there an equation for the median or the percentile?
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### model_count error in ZINB r pscl analysis

I am modeling a mediated zero-inflated negative binomial (ZINB) model. I am following the steps of O'Rourke & Vazquez (2019) A few days ago I was running a different ZINB model which ran ...
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### GLMM: Define zero inflation varying across sites

I am fitting a glmm for count data as follow: ...
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### Weighted zero inflated negative binomial regression

Before encountering the ZINB model, my choice of model was the standard NBR model with the R function glm.nb. My dependent variable is non-negative integer in ...
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### Zero-inflated mixed models and negative trend in residuals

I am trying to fit a mixed model in lme4 using the lmer. the model form is: model<- lmer(entropy ~ X1 * X2 + (1| video) + (1| subject), REML = FALSE entropy ...
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### Can I model my analysis as a negative binomial regression problem?

I am working on a research project to identify the individual impact of dominant personalities, and sexual esteem on sadistic behavior. I am also completely new to statistical analysis. Both of my ...
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### What is a right definition for “nested models” in Zero Inflated Poisson?

Suppose I have 2 models: ...
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### Zero inflated generalized poisson: How can I compare 2 models?

I'm using Statsmodels to fit count data by Zero Inflated Poisson Regression. Suppose that I have 2 models: ...
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### how to compute the prediction standard error of zero-inflated count data regression using R

I have count data and explanatory variables. I can use the pscl R package to do a ZINB regression thanks to zeroinfl. I'd like ...
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### Two-part model: is it necessary to use the same regressors in both parts?

I am implementing a two-part model where the first part is a probit/logit and the second part an OLS. Is it necessary to use the same regressors for both parts or can I use different variables? In ...
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### Misleading Estimated Marginal Means in Zero-inflated Mixed Models

I am working with a number of zero-inflated poisson and nbinomial mixed models (with an offset), but when I produce estimated marginal means from them they are sometimes many orders of magnitude ...
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### How to deal with overwhelming presence (or absence) of particular values on a sliding scale?

I have data from a sliding scale with values from 0 to 100 (not my choice of instrument, but it's what I have). The scale has a default value of 50. Participants respond on the scale before (pre) and ...