# 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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### Regression assumption

I have a data set where $100$ people made $500$ trips for $5$ days. I want to build a trip-level regression (zero-inflated Poisson) where the dependent variable will be the count of hard-braking in ...
789 views

### Can you use glmmTMB to simultaneously model offsets and zero-inflation?

I'm currently modelling microbial data, with multiple samples and groups of samples. Two problems arise with my data: 1) The data is zero-inflated and dispersed (large variation); 2) Each sample has a ...
81 views

### Dirichlet-Multinomial Distribution with many zero counts

Short version: Is there someway to make the dirchlet-multinomial distribution sensitive to the presence of zero counts? Long version: I am attempting model metric positions in musical data. You can ...
41 views

### Model and predictor selection in generalized linear models

I’m analyzing count data in R and I want to make two decisions: 1) what type of regression to use (Poisson, negative binomial, zero-inflated, etc), and 2) what predictors to include in the model. I’m ...
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 ...
164 views

### What approach can I use to analyse zero-inflated, overdispersed, count data with very low replicates and a nested random effect?

I am having trouble with analysing some of my data. I'm trying to test the effect of a treatment with two levels (Treatment/Control) on the abundance of ants belonging to different dominance ...
121 views

### Classification followed by regression?

I have the following problem: I have a dataset for which my observations have a bunch of features and a continuous response (regression problem). However, some of my observations (about a fourth of ...
43 views

### how to model this type of distribution?

I am trying to model this distribution in a generalized mixed model. the variable is a measure of number of number of years, reflecting start to end of reproduction, i.e. reproductive period. This ...
382 views

### How to handle Zeros in dependent variable in Multiple Linear regression

I am totally new to machine learning (and to this platform too) and was trying to implement Multiple linear Regression to improve my ranking algorithm. I have a data-set which have the following ...
61 views

### Linear Regression with both variables centered on 0

Just a question to be sure, if my dependent variable and independant variable are centered on 0, how do I interpret correctly the linear regression ? The intercept must be significant for the slope ...
242 views

### Zero inflation Poisson regression

I am using penalised methods based on glmnet package in R. I used the zero inflated Poisson regression for my sample which contains 2,734 observations and 27 ...
1k views

### Distribution with zeros that is lognormal without zeros

I have 79 observations with 30 as first quartile, 50 as median, 50.5 as mean, 68 as third quartile. Max value at 169, min value at zero. In particular there are only 4 observations at zero. The ...
193 views

### Measure of relationship between two variables that are percentages containing many zeros

I am working with various different data sets (in the context of forest reclamation on industrial disturbed landscapes) that contain percent cover values of desired (planted) and undesired plant ...
315 views

### Generate zero-inflated random vector

I want to randomly generate a vector of size n - that represents hypothetical revenues per users in a webshop. Typically I would imagine this distribution to ...
1k views

### hurdle model with non-zero gaussian distribution in R

I have biomass data (continuous response variable). If sufficient data is collected, the log(Biomass) follows a normal distribution. However, I am separating the overall biomass by family (i.e., ...
149 views

### How to model wind speed with a weibull distribution when there is excessive zeros in the distribution? [duplicate]

Hey I have a data set that contains hourly wind speed for about seven years. I am trying to model the data using a weibull distribution which according to literature is a good fit for hourly wind ...
58 views

### Testing significance between samples with all zeroes in one

I have Count data with zeros, and I'd like to use a poisson GLM (or similar) to compare two groups. One group has all zeros, the other is count data ranging from 0-15. Since one group has all zeros –...
79 views

### Random effects in ZIP or ZINB models - count portion, Bernoulli portion, or both?

I'm building some zero-inflated models that need to include random effects, and I can't find a definitive answer for whether I should include the random effects in the part of the model that describes ...
49 views

### Fitting zero inflated right truncated negative binomial distribution

I have a dataset that is bounded above by 2000 (physically not possible to have larger than 2000 values). Is there a way, in R, to fit a zero inflated, upper bounded negative binomial distribution to ...
334 views

### How to do preprocessing for zero inflated variable in multiple regression?

I am trying to build a multiple regression model, and many of my variables looks like this (histogram for time spent in the system). The reason I had such data is because zero is actually represents ...
31 views

### Computing cost-per-use for a zero-use item with sunken cost

The very idea of a cost-per-use (CPU) analysis implies that either all units have use, or that cost is incurred only with use. However, there are situations where neither of these situations hold true....
597 views

### Overall p-value for zero-inflated beta regression mixed model

I am analysing vegetation percentage cover data from grazed and ungrazed plots in R using a zero-inflated beta regression in package gamlss. Here are some example ...
93 views

### Hurdle model with weighted count variable as dependent variable?

My question concerns the feasibility of applying a hurdle model when my dependent variable is not exactly a count, but a "weighted count". More precisely, my weighted count variable (...
195 views

### Posthoc test for zero-altered models (hurdle, ZNAB)

I have created a zero-altered negative binomial model (ZNAB, using the hurdle function in R). This model consists of two parts, one which analysis zero values, and the other analysing positive values ...
89 views

### What do two spots mean in the GLM model validation graphs?

I performed a hurdle (delta) model to estimate the relative indices of abundance of a fish species. Thus, the catch estimates involved fitting separately two ‘sub-models’ to the data. The first sub-...
36 views

### Comparing several Poisson Models [duplicate]

I have training data that I have fitted with two types of Poisson models (one zero inflated and one standard) and I would like to compare each model's performance on a test set to see which one is ...
4k views

### Is a “hurdle model” really one model? Or just two separate, sequential models?

Consider a hurdle model predicting count data y from a normal predictor x: ...
354 views

### Likelihood ratio test with zero inflated models to check overdispersion

I am trying to compare ZIP and ZINB models and see if there is an overdispersion. They have the same parameters except alpha. I am wondering if it is correct to use Likelihood ratio test, the same way ...
67 views

### Count regression with censored counts that aren't necessarily zero.

Say you have count outcomes $Y_1, ..., Y_n$ out of different population sizes (e.g. offsets in a usual count model) $p_1, ..., p_n$. I want to relate this to a covariate $X_1, ..., X_n$ using a usual ...
126 views

### Should I use post-hoc tukey HSD or some other test for pairwise comparisons of a factor on a zero-inflated negative binomial mixed model (ZINB)?

I ran a zero-inflated negative binomial mixed model (ZINB) and now have a statistically significant factor (recording type, either NOCA, BCCH, or Human). To assess the differences between these three ...
4k views

### Forecasting daily time series with many zeros

I need to forecast a univariate time-series of sales data with the following characterica. It is a daily time-series Around 70-80 % of the date nothing is sold ($x_t = 0$) At the 20-30 % remaining ...
220 views

### Steps of a clustering problems composed by right-skewed data and large number of zeros

I'm trying to cluster a dataset based on 190 diabetic patients and 20 columns (features of patients) and many of these features have most zeros (to understand better, the median of 8 of 20 features is ...
5k views

### Interpret zero-inflated negative binomial regression

I am trying to estimate a zero-inflated negative binomial model with 11 predictor variables and the number of reported crimes as a response variable. The model seems to work OK, but I'm uncertain on ...
86 views

### sjstats- Model is overfitting zero-counts

I have a glmmTMB model and I used the overdisp and the zero_count functions with these results: ...
668 views

### deviance for zero-inflated compound poisson model, continuous data (R)

I am looking at homicide rates per US county in a given 3-yr period as a DV, against several demographic and political measures as IV. I have A LOT of zeros for the DV, and these are presumably real ...
268 views

### zero inflated poisson model, how to choose “inflate” variables

I am trying to run a zero-inflated Poisson regression. The data I have are number of West Nile Virus cases NoCases (dependent var), and my independent variables are AvgTemp, AvgPrecipitaion, Region (*...
2k views

### How to forecast demand with time series and/or other models?

I need to forecast data which has many periods of zero demand, also there is no seasonality or trend in the data. I tried ARIMA, but it converges to the mean. I also applied some predictors, but ...
3k views

### Zero inflated beta regression using gamlss for vegetation cover data

My goal is to analyse vegetation cover data. The way the data collection works is that you throw a quadrat (0.5m x 0.5m) in a sample plot and estimate the percent cover of the target species. Here is ...
135 views

### Hierachical cluster analysis of ordinal variables?

I have a dataset containing 400 variables (chemical compounds, amount classes) with values 0,1,2, or 3 and 50 entries (species). Can I use hierarchical cluster analysis to get a dendrogram that ...
255 views

### Network architecture to predict zero-inflated output

I have a dataset of debt collections and I am trying to predict how much each person paid. The paid amounts are greatly zero-inflated. In the past I have built a two-stage model predicting the ...
231 views

### Transformation of data with 0 values

I've read some of the comments about trying to do log transformations on data that has 0 values. In my data I have two treatments that would be helped with a log transform except each treatment has a ...
757 views

### Residuals in Zero-Inflated Negative Binomial Regression

What do residuals mean in the context of zero-inflated negative binomial regression? I'm learning zero-inflated negative binomial regression. The data is from a state education system and includes ...
604 views

### Dispersion parameter in mass and PSCL package (zero-inflated negative binomial and negative binomial)

I have run Zero inflated negative binomial and negative binomial model with same data set in R. I get log(theta)= -2.47 for Zero inflated negative binomial and log(theta)= -5.149 for negative binomial ...
404 views

### generation of zero-inflated Poisson data in R

I want to generate data from a zero-inflated Poisson distribution in R using the mpath package in the following way: ...
298 views

### How to fit Anomaly Detection model to imbalanced time series data(Zero Inflected time series data)?

I'm doing a predictive modeling for predicting anomalies in the sensors data. For this I'm using the twitter AnomalyDetection package in R. We are getting ton of data from sensors for every day. For ...
177 views

### Zero in proportion data

I am counting the proportion of seeds that have germinated (RV) in petri dishes. 5 petri dishes each had 25 seeds in them. Treatment (EV) was applied. No seeds germinated. When this is put through the ...
574 views

### Fitting custom distributions by MLE

My question relates to fitting custom distributions in R but I feel it has enough of a probability element to remain on CV. I have an interesting set of data which has the following characteristics: ...
65 views

### How can I compare two variables when one has lots of zeros?

Specifically, I want to understand the contributions to insurance premiums and claims. In this case, everyone pays a premium, but only some people make claims. I want to understand whether the ...