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).
386
questions
1
vote
1answer
320 views
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 ...
1
vote
1answer
1k views
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 ...
1
vote
1answer
669 views
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 ...
2
votes
0answers
99 views
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 ...
-1
votes
1answer
121 views
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 ...
2
votes
0answers
75 views
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 ...
0
votes
1answer
64 views
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 $j$, ...
4
votes
2answers
2k views
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).
...
1
vote
0answers
173 views
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), ...
3
votes
0answers
325 views
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 ...
3
votes
0answers
527 views
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 ...
9
votes
2answers
668 views
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 ...
5
votes
1answer
644 views
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 ...
2
votes
1answer
649 views
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 ...
1
vote
0answers
515 views
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 ...
1
vote
0answers
382 views
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 ...
0
votes
1answer
359 views
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 ...
1
vote
0answers
80 views
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. ...
1
vote
0answers
143 views
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,...
1
vote
1answer
843 views
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 ...
4
votes
0answers
3k views
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 ...
3
votes
0answers
531 views
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 --...
2
votes
0answers
81 views
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.
...
1
vote
0answers
162 views
Predicted values in negative binomial model with 0-inflation
My count data are zero-inflated, for which I utilized glmmADMB.
...
2
votes
0answers
186 views
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 ...
2
votes
1answer
60 views
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 ...
2
votes
0answers
152 views
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) ...
2
votes
0answers
179 views
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: ...
1
vote
1answer
4k views
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 ...
0
votes
1answer
2k views
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 ...
5
votes
0answers
636 views
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 ...
1
vote
1answer
412 views
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 ...
1
vote
0answers
539 views
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)
...
1
vote
0answers
26 views
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 ...
3
votes
1answer
4k views
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 ...
1
vote
0answers
452 views
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 ...
3
votes
0answers
3k views
Zero-Inflated Poisson Regression – Warning message: In sqrt(diag(object$vcov)) : NaNs produced [closed]
I'm trying to model the following data:
using zero-inflated poisson regression:
model <- zeroinfl(dv ~ c1 + c2 + session | participant, data = dat)
where dv ...
1
vote
1answer
332 views
ZIP Fit Indices Calculated from an EM Algorithm
I am working through @ben-bolker's owls example available here:https://groups.nceas.ucsb.edu/non-linear-modeling/projects/owls/WRITEUP/owls.pdf
In particular, I am making use of the R ...
1
vote
0answers
298 views
sample size to estimate mean of zero modified log normal variable
I would like to estimate the average value of a variable "A" in a population. I think only 5% of the population has a figure of A > 0, 95% has A = 0. Using a previous non random sample, I believe the ...
11
votes
1answer
936 views
Measure of “deviance” for zero-inflated Poisson or zero-inflated negative binomial?
Scaled deviance, defined as D = 2 * (log-likelihood of saturated model minus log-likelihood of fitted model), is often used as a measure of goodness-of-fit in GLM models. Percent deviance explained, ...
2
votes
0answers
167 views
Combining Exponential and Bernoulli distributions [closed]
I am building a model of customer spending, and need some help to identify the best way of doing this.
(1) I have an exponential distribution for each customer's spending
(2) Bernoulli distribution ...
2
votes
1answer
4k views
GLM - Zero-Inflated distribution
I'm fitting a zero-inflated poisson model using the "pscl" package. The formula that I'm using is:
...
2
votes
1answer
772 views
Rules for Percentage of zeros in a zero inflated model
What percentage of zeros in the data should make us consider trying the sequence of models: Poisson -> Negative Binomial -> Zinf-Poisson -> Zinf-Negative Binomial, etc? I have two datasets with about ...
4
votes
0answers
463 views
How to write unnormalized posterior when prior is a mixture of continuous and discrete
Suppose I want to do bayesian inference on the regression problem $\beta$ for Y = X$\beta$ + $\epsilon$ for $\epsilon_i \sim N(0,\sigma^2)$. The complication is that the prior for each component $\...
0
votes
1answer
799 views
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:
...
1
vote
0answers
851 views
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 ...
7
votes
1answer
4k views
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 ...
15
votes
1answer
16k views
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 ...
0
votes
0answers
214 views
SEM with zero-inflated outcome
I'm working on a project and my advisor wants me to do SEM in MPLUS because we can do latent modeling, but I have no clue where to start. I've only ever done regressions but I said I'd be up for ...
3
votes
1answer
942 views
Multicollinearity in Zero Inflated Negative Binomial Regression
I am trying to model counts govt, based on the counts lp,const,...
