# 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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17 views

### How to interpret the hurdle or zero-inflated model

I have 137 data points that are inspection and I'm trying to find the hurdle negative binomial distribution that fits. Here is how the data looks I have the following code ...
34 views

### Can we perforn a permutation test with zero-inflated data?

In a collaborative problem-solving task, I would like to check if the mean number of communicative exchanges emitted by a person is different following whether they shared an emotion just before or ...
47 views

### Zero Inflated Poisson model, estimation of vectors beta and gamma

I'm working on zero inflated poisson models but I have a doubt on the estimation of the coefficients. Suppose that I have a small sample of data (just for an example, 10 policies with just 4 ...
19 views

### Nested Negative Binomial (or zero-inflated) Regression

I am currently working on methods for a thesis project. I will be modeling the outcome of disease incidence for two different diseases using negative binomial regression. It will most likely be zero-...
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### Zero-Inflated Negative Binomial Theta and Incident Rate Ratios (IRR)?

I am trying to determine the best regression model for data with many zeros; I have about 200 with non-zero DS scores and 600 with zero DS scores. ...
31 views

### What is the difference between a Zero-inflated negative binomial regression and a Heckman-two-step regression model?

The title of my question says pretty much what I'm struggling to understand: What is the difference between a Zero-inflated negative binomial (ZINB) regression and a Heckman-two-step regression model?...
79 views

### Interpreting random effects in zero-inflated models

For context, I have a longitudinal study measuring counts of bacterial sequences in human stool collected during a dietary intervention. Initially, I was going model the change in each bacterium (...
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### Zero inflated and hurdle models - is it common do 'build your own' with e.g. ensemble model?

I have been given a new analytics problem to solve. The context is app analytics where we would like to predict total revenue per app install after 30 days from install based on just 7 days of data. I....
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### One group has only zero values, should I use parametric or non-parametric test?

I have 3 groups (n=5 per group) from biological data. I have checked the normality of my groups using the Shapiro-Wilk test and two of my groups are normally distributed. However, the 3rd group values ...
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### Handling large percentage of zero-valued observations in a continuous dependent variable in a panel dataset

I am writing a paper using a panel dataset in which my depepent variable is continuous has an large percentage amount of zero values observations. Those zero values are real zeros, I mean they are not ...
48 views

### Multivariate zero_one_inflated_beta regression

I want to run a zero_one_inflated_beta regression with brms on the following multivariate formula: ...
59 views

### JAGS code for Poisson or negative binomial hurdle (zero-altered) model with autoregressive residual

I am using Bayesian zero-altered Poisson and negative binomial models analyzing time-series data with JAGS. Because the ACF of the Pearson residuals showed autocorrelation, I decided to apply ...
64 views

### Statistical tests for count data with many zeros

I have to compare three groups (each group is a customer to a subscription box company). Group A received treatment A. Group B received treatment B. Group C received no treatment. We count the ...
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### Unusual residual artefacts in GLMM, is GAM or another model more appropriate?

I'm having trouble finding an appropriate model for my data. The data comprises behavioural observations of chimpanzees, where I instantaneously sampled their locomotor behaviours and parameters of ...
134 views

### Interpretation of zero-one-inflated beta models in brms

I have 20 participants who have watched 18 clips. Every clip belongs to one category of pleasure (p_cat: negative, neutral, positive) and one category of intensity (i_cat: low, medium, high). I have 2 ...
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### How to analyze data with unequal length of observations and many zeros?

I want to analyze the impact of the rain on smoking probability. I observed people in two cities on the streets and marked the following parameters: city, gender of the person, duration of observing ...
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### How to obtain different values of “parameter k” in a mixed-effects negative binomial model?

I have a dataset with two level factors - fertilizers ("Nitrogen" or "Phosphorous") that differed in their concentration level("...
42 views

### Poisson on frequency data with many 0, underestimated output

I have got a frequency table of how many events occur within a 5-minute time window. ...
41 views

### Extracting the right summary statistics from zero-inflated data sets (i.e. a sparse matrix where everything non-zero is a statistical outlier)

I'm a consumer tech startup founder with rudimentary background in statistics. I need help in processing a large, sparse matrix. I'm logging all actions users are undertaking in my app. I then ...
53 views

### How to deal with zero-inflated proportional data in GLMM?

I have proportional data, i.e. number of individuals out of 6 that choose a certain option in a multiple choice experiment, so there are just 7 possible outcomes for each option: 0/6; 1/6; 2/6; 3/6; 4/...
48 views

### Inferences from a zero-inflated negative binomial distribution?

Frogs are generally known to spatially aggregate during egg-laying. I manipulated their egg-laying sites with different fertilizers ("Nitrogen" or "Phosphorous") that differed in their concentration ("...
64 views

### analysis of variance on zero inflated semi continuous data

I have a fairly fundamental problem with my data, they do not suggest that they were sampled from a normal distribution. This is problematic because I would like to run some sort of analysis of ...
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### What model is appropriate when a non-negative, continuous dependent variable has frequent zero-values because of limited data?

I'm modeling how likely a song is to occur in a playlist with a particular title. I can calculate a simple probability based on my current data, but it's highly zero-inflated because my data is ...
21 views

### zero inflated interval data

looking at the survey my data set is based on, my dependent variable originally is given in percentage ranging from 0 to 100. Howewer, in my dataset the information is categorized in to 9 intervals. 0 ...
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### What is the impact of excess zeros on poisson regression coefficient estimates?

The background I have a dataset with some zeros - based on how I segment my data, it is either 50% of the observations or 80% of the observations. The data is not actually count data, but from what i ...
220 views

### Variable selection in zero-inflation models

I am trying to understand how to perform model comparison between different count models. In this example the author performs a zero-inflated poisson model testing the effect of number of people in a ...
63 views

### How to plot estimate + raw data of a Bayesian zero inflated poisson?

GENERAL QUESTION: How to back-transform estimates from a zero-inflated poisson to obtain the original scale in R? (I tried exponential like for poisson but the results are wrong) DETAILED ...
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### R - zero biased data, glmer.nb, properly counting confidence intervals

any suggestions how to count confidence intervals from zero biased data? I've counted generalized linear model using glmer.nb function. I have to make graph but I was told that confidence intervals ...
132 views

### How to model a zero-inflated 'continuous' response data in r 'without' assuming an underlying normal distribution?

I have a weather data set with rainfall as response. It has 56% observations as 0, while the rest as continuous rainfall data. I can't use tobit, hurdle or any other zeroinfl() model as they require ...
24 views

### How to calculate ICC for a zero-inflated negative binomial model

I did a zero-inflated negative binomial regression on some data. However, the data is nested (students within schools), and I would like to calculate ICC to make sure that we did not need to take this ...
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### How to optimize statistical approach in terms of reducing number of statistical tests used?

I need to analyse second step care among very heterogenic patient population whose second step care is also very diverse. I can do this using multiple models and tests (up to 10), but this is just too ...
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### Approach to Analyzing Semi-Rare Events

I am often faced with analyzing data that follow a pattern as shown in a mock example in the image below. Key data characteristics: for any value of the predictor (e.g. temperature), the most ...
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### Hurdle model vs left censored model

When dealing with response variables that have lots and lots of zeros, is there a clear argument for when hurdle models are preferred and when left censored or tobit models are preferred?
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### What regression type for Normal DV and count data IV (with lots of 0s)

I'm performing regression on subjects' response to a question on a 1-5 likert scale (1=low, 5=high, etc)- This is the DV and its continuous and normally distributed. The IV is a count of how many ...
248 views

### Model selection: Two-Part Mixed Effects Model for Semi-Continuous Data

I have now been studying mixed models for about a month, I am still a pure beginner. I have zero inflated semi continuous dependent variable (yield of trees between two periods). Exploring ...
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### How to interprete the p values of cos and sin terms in periodic regression?

I have camera trap data where for each site and hour I have the abundance of wild herbivores. I want to create a model where I can estimate the effect of predator activity on the activity and behavior ...
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### Choosing error function for regression

I have a dataset with ~100K samples and non-negative continuous target variable. 99% of target values are zeros and the remaining 1% are right-skewed. Here are the deciles (0 and 1 correspond to min ...
29 views

### Extremely large (>10000) value of theta in hurdle model

I am estimating a hurdle model with a binomial (first stage) and truncated poisson distribution (second stage). The results look fine but I have a very large value of theta (greater than 10000). I ...
20 views

### How to model zero-inflated mass data? [duplicate]

I am working with a data set of the mass of plastic found at various sites. At most sites, we found no plastic and so the data is zero-inflated (see histogram below). I want to model the data using ...
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### Zero-inflated Poisson regression with unit and time fixed effects (Application in R)

In much need of some assistance. My question concerns the conceptualization of zero-inflated Poisson regression in a two-way fixed-effects settings. I have crime data and my outcome is 'count' ...
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### Conflicting residual diagnostics for GLMM for binary data: zero-inflation

I fitted a mixed logit model with crossed random effects in lme4_1.1-21::glmer to some experimental binary data. The maximal random-effect structure justified by ...
19 views

### Computational error for zeroinflated negative binomial regression model

I am trying to fit a zero-inflated neg. binomial model. I have many predictors for the count model, but only one for the zero model (Saturday). ...
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### Zero-inflated model with no variation in the outcome

I want to fit a zero-inflated neg. binomial model using zeronfl(outcol ~ vm + Thursday + Saturday |Saturday + Thursday + vm, data, family="negbin") from the pscl ...
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### How to conduct a principal component analysis on data set with large number of zeros

I have data for percentage cover of plant species in 500 sites. There are columns for 30 different species in the data set and I would like to drastically reduce this down to a manageable number of ...
54 views

### Which model should I use? (genomic problem)

I have problems with choosing which model / link function should I use for my analysis. My response: numbers from -100% to +500% (increase of tumor after therapy, may switch to ratios or log-ratios, ...
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### zero inflated presence absence binomial GAM in R

I am fitting a binomial GAM using mgcv in R. My data is presence (1)/ absence(0) of dolphin acoustic detections in 10 minute time windows over ~1 year period. However, I have only ~750 presences to ~...
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### DHARMa diagnostics: testDispersion and testZeroInflation interpretation

I have been analyzing count data using Poisson distribution in glmmTMB, and just ran some DHARMA diagnostics. However, there don't seem to be a lot of help online on how to interpret the results. Does ...
29 views

### Statistical specification for a Regression with continuous finite range count like data

I am interested in explaining what kind of personal characteristics and work environment variables are associated with sickness absenteeism. My dependent variable is the total number of days a given ...