# 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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### Test diffrances of means in zero inflated, non normal distribiution

I have a big number of clients, that can be either treated with and ad (target group) or no (control group). The purchases after set amount of days are drawn from zero inflated (>50% of zeros) ...
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### Selecting between a zero-inflated binomial, OLRE and beta-binomial model

I need some help in deciding which of the following models fits best the data that I have. This was a survey where participants reported proportions of successes (defined as n/m) in condition A and B. ...
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### How to fit simple count data to model in order to generate new dataset

I have simple count data set in a form of data vector PC6. I am trying to identify distribution in order to create pseudo generator for my simulation. Freq table of my data is ...
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### How does one typically present negative-binomial hurdle model results in a table?

Context of the data: I have over-dispersed counts of an insect on leaves. These leaf counts come from two groups: treated and untreated. I was initially reluctant to simply express the treatment ...
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### Are zero inflated models appropriate if the predictor/x variable is the one that is zero-inflated?

As the title suggests. I was under the impression that zero-inflated models are generally used when zero values are over-represented among the response/y variables, but now I am dealing with a ...
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### Zero-inflated negative binomial model standard error too high?

I've been trying to analyze count data for ant foragers visiting on extrafloral nectaries with R. My data is both overdispersed and zero-inflated, so I used a zero-inflated negative binomial model to ...
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### How are zeros treated in two-part models for zero-inflated variables?

Two-part models for zero-inflated outcome variables seem very useful. Zero-part of that model seems quite straight forward, something like logistic regression with a binomial, zero vs non-zero, ...
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### Double-hurdle model with negative values (no count data)?

I am searching for a model for the following experiment: Subjects have to allocate money (say 100 Dollar) between 2 hypothetical friends. Subjects have to allocate in each round 100 Dollar. In each ...
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### Zero inflated Count Data treatment with XGBOOST

I am planning to run an xgboost in response data that is: Count data (0 to 15) Very right skewed Zero inflated (lots more zero than other counts) In the XBG package with R, I have specified count:...
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### How to graphically diagnose conditional zero-inflation in count response regression?

Is there any ubiquitous (or not so much) graphical method in count response models (e.g. Poisson GLM) to diagnose conditional zero-inflation? I'm aware of statistical tests that can be used for that, ...
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### What's the opposite of a zero inflation model?

I have an ecological dataset of capture-recapture encounters. I don't have any 0 occurrences because if an animal was not encountered, it was not noted in the dataset. Thus, my dataset doesn't have ...
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### Determining if data is zero-inflated

I am attempting to use the check_zeroinflation() function from the performance package in R to determine if my count data is zero-inflated and I was wondering what the ratio in the function output ...
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### Interpreting a zero-inflation negative binomial model

I am currently running a series of zero-inflated negative binomial models on the impact of the magnitude and direction of change in various weather parameters on a number of insect behaviours (...
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### Interepreting zeroinfl and glm.nb from my dataset

I am testing 4 predictors on overdispered count data with many zeros. The problem I am having is whether I have set-up my model correctly. my current model of ...
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### What's are some good way to report main effects in time*treatment models without a significant interaction?

There are many similar questions posted on this website but also a wide variety of conflicting answers, so I'm still unsure of the best way to proceed. I have several independent but similar datasets ...
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### Error in a zero-inflated negative binomial model?

Following DHARMa diagnostic tests revealing zero-inflation (ratioObsSim = 32.663, p < 2.2e-16) and over-dispersion ...
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### Zero-inflated poisson/nb — which covariates should I put in the inflation (logit) model and which should I put in the count model?

I'm using a zero inflated count model (either poisson or negative binomial). I have a set of control variables that I want to include in addition to the main independent variable of interest. Can ...
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### How do I interpret this hurdle model summary (pscl)?

A little bit about my data: I have four treatment groups: control, early, late, both. For each group, I counted nymphs and eggs on leaves on five different dates. The design is randomized complete ...
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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 ...