Count data are non-negative integers representing whole amounts. When such data are the dependent variable in a regression, Poisson or negative binomial regression may be appropriate methods. One common problem is "zero-inflation" (where the proportion of zero values is greater than predicted by a ...

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2
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17 views

Modelling overdispersed counts - past negative binomial

I'm modelling overdispersed counts. I began using a GLM with Poisson error structure, then moved to quasi-Poisson, and then finally negative binomial. The residuals versus fitted values plot is still ...
2
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0answers
19 views

Estimate lambda for panel count data

I have panel count data for $F$ firms across $I$ years, so observe counts $C_{f,i}$ for $f \in \{1,...,F\}$, $i \in \{1,...,I\}$. I want to model the data as a poisson process. With increasing ...
1
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0answers
9 views

How can I test for autoregressive residual terms in a fixed effects panel Poisson model?

I have panel data for counts of new firms in different regions for six years. I am estimating a static poisson regression with multiplicative fixed effects$^*$; I have also tried to estimate a dynamic ...
0
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1answer
26 views

Normalize counts over time without adding excess variability

I'm not quite sure if this is possible to do, but I have count data that I would like to put on a similar scale in order to compare it. We are tracking where people go, and want to see if people who ...
0
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1answer
27 views

What regression model or test is better for modeling commuting data?

I have count of people commuting from an origin to a destination as my response/dependent variable. The independent variables are travel time (in minutes) and travel distance (in kilometers). I have ...
1
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0answers
19 views

Correlation between counts

I'm trying on attendance data to find relationships between where people go. For example, say I have information on users A, B, C & D and what kinds of places they've visited in the past few ...
0
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0answers
18 views

Software or workarounds for vector autoregression on count data?

I have a research question that fits nicely in a VAR framework but my data are count data. They are much closer to a Poisson or negative binomial distribution than they are to a normal. This will ...
0
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0answers
43 views

What significance test to use for count data?

I have TRANSFAC data of number of transcrption factor binding sites(TFBS) for each gene. I have ~1100 Transcription factors (TFs) and 2 sets of genes: 18 genes belonging to Pigmentation AND 5 genes ...
0
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0answers
13 views

Logarithmic offset + Scaling Counts + Multiplying by Scalar + Poisson Regression

I am working with a contingency table where I know that the population sizes from which the counts are derived are very different. From what I have been able to gather, an appropriate way to adjust ...
1
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0answers
21 views

Should predictions with negative binomial regression only produce integers?

I have a dataset consisting of about 600 observations. Each observation has around 100 attributes. One of the attributes I want to predict. Since the attribute that I want to predict can only have ...
1
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0answers
45 views

Regression models to only predict integers (instead of floating point numbers)?

I have a dataset that consists of about 50 different attributes. One of these attributes I want to predict, using the other attributes as features. The values of the attribute that I want to predict ...
1
vote
1answer
31 views

Alternatives to Chi-Squared for Single Categorical Outcome and Single Categorical Predictor w/counts for factors [R]

I am from an applied background, where X2 and G-tests are the default ways to analyze count data (default as in, until today, I had no idea there were other ways, as I was only taught these methods). ...
3
votes
1answer
95 views

Statistical comparison between binomial distributions, two groups and many trials

I have a data set with two groups. I have multiple trials with different Ns in each trial, and different numbers of trials for each group. In each trial, for each ...
1
vote
1answer
75 views

Using linear regression for count data - will this introduce bias?

Say I am fitting a model to Poisson count data, but I am only interested in estimating the mean of the count variable. I understand a ordinary linear regression is a good approximation when the ...
0
votes
0answers
13 views

Percentage/Mixture data with many zeros

My dependent variable is continuous. My independent variables can be looked at in two ways. In the first, they are a bunch of count data with a large cluster at zero. In the second way, we can ...
1
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0answers
26 views

Factor Analysis of Count Data

I am new to factor analysis. I inherited a project at work from another team. They took 9 variables that are all Poisson-distributed count random variables and ran a "regular" factor analysis in ...
3
votes
1answer
56 views

Use of Poisson distribution to analyse distribution of individuals in space

Dytham 2010 suggests using the Poisson distribution to establish whether individuals are evenly distributed in space. Say we end up with a map of individuals in a study site that looks like the ...
2
votes
2answers
113 views

Am I breaking the assumptions of the Poisson distribution?

The Poisson distribution arises when events are counted within a specified interval. I've recorded the number of events each month (I'll not discuss what these events represent). This appears to meet ...
2
votes
2answers
56 views

Help on deciding how to perform a regression analysis on my data, and why? SPSS, Count model, Panel data

I am currently in the process of analyzing some data for my master thesis, however I have had little statistical teaching, and none regarding panel data regressions. My dependent variable: Count data ...
0
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0answers
11 views

Is a gaussian mixture appropriate for TF-IDF?

I'm trying to fit multivariate mixtures of TF-IDF scaled variables. So these variables are weighted count proportions of words in a corpus (relative frequency in document weighted by the log of ...
10
votes
1answer
502 views

When to use Poisson v. Geometric v. Negative Binomial; GLM, the Three Count Variable Distributions

I'm trying to layout for myself when it's appropriate to use which regression type (geometric, poisson, negative binomial) with count data, within the GLM (only 3 of the 8 GLM distributions are used ...
0
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0answers
23 views

Modeling count data [duplicate]

Why do count data need to be modeled differently from the standard linear regression model ? Any simple example will suffice.
11
votes
1answer
280 views

significance of difference between two counts

Is there a way to determine whether a difference between a count of road accidents at time 1 is significantly different from a count at time 2? I have found different methods for determining the ...
0
votes
2answers
29 views

how best test for differences among two samples of abundance (count) data measured at the same sites

I want to test for differences in the abundance (counts) of two types of lizards. Both types were sampled at the same sites (n=284). The distribution of both types is overloaded with zeros and lizards ...
0
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0answers
36 views

What can go wrong if I use normal 2sls IV regression for count data?

My dependent variable is count data and for explanatory analysis we used a negative binomial regression. One variable is endogenous and we would like to instrument it. However, in Stata there is only ...
1
vote
1answer
31 views

Running Latent Dirichlet Allocation (LDA) on word counts

I have difficulties understanding the VB implementation lda-c. In particular, the method expects as input a bag-of-words representation of documents, where distinct words appearing in a document are ...
1
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0answers
42 views

How can I model such count data with underdispersion

Here is an example of my data: 2 6 4 5 2 5 4 4 2 3 3 5 5 6 5 6 15 19 16 9 14 14 11 10 6 4 2 In my assumption, the sequence can be separated into regimes, for instance, 2 6 4 5..6 6 5 6 belong to the ...
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0answers
25 views

What method is appropriate? - analysing patterns of attacks by region

I am currently working on a project using a dataset on global terrorist attacks. For each attack there are details on the type of attack which has 7 levels (e.g. bombing, assasination etc.), the ...
2
votes
1answer
48 views

How to categorize count data

I have count data (basically histone modification data). The counts represents number of reads falling into each genomic region. I need to divide my data into $\text{low|medium|high}$ based on the ...
0
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0answers
22 views

Quantifying 1 factor count data with variable # of categories

I feel like this should be an easy question, but after lots of looking I"m stumped. I deal with continuous data almost exclusively, but in my infinite wisdom I designed this study that yielded ...
0
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0answers
37 views

Can I use SAS Copula procedure or Matlab copulafit to fit count data (Poisson or Negative Binomial)

I want to simulate data (x,y) with dependency using copula. Matlab has the function for t copula, Clayton, Frank, and Gumbel bivariate Archimedean copulas. But I am not sure if these functions could ...
0
votes
0answers
18 views

Which reliability index (if any) is appropriate?

Subjects were asked to endorse whether or not they have experienced various negative events (yes/no). I want to use a measure that is a sum of how many events they have experienced. Since this measure ...
0
votes
0answers
67 views

Which model for under-dispersed data? Effect of poverty on adaptive capacity

I am working on the specific effects of poverty on farmers' adaptive capacity in sub-saharan Africa (N=1211). In bivariate, two of my poverty measures have an non-linear relationship with adaptive ...
0
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0answers
15 views

resources for temporal count data

I am currently in the middle of analyzing count data. The count data is gathered once per day for more than 100 days. There are two populations that are counted everyday. Is this type of count data ...
0
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0answers
57 views

Selecting best count model using Stata's countfit?

I am using the countfit command in Stata 13 to determine which count regression model is the best fit for the a model of number of current domestic migrants, with independent variables: workers in ...
0
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0answers
17 views

Using count data with number of days

I have two populations A and B. The data consists of count data per number of days after an event has occurred. For example: ...
0
votes
0answers
54 views

Multiple comparison for model fit with glmer

I would like to use glmer to fit a model of seed count data, and then compare the means from each plant line at two different temperature regimes. I am really not sure how to go about doing the ...
1
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0answers
37 views

Estimating confidence intervals on count data from classifier output on varying populations

I have a widget factory which produces a varying number of widgets each day. Every day, I need to report the number of faulty widgets. But the proportion of faulty widgets is expected to change every ...
2
votes
0answers
25 views

Identify deviations from trend

I have a panel with individuals $i$ measured at time $t$ (the date). The outcome is a count, which we can call $C$. There's some general time trend $g$ affecting all individuals. $E[C_{it}] = ...
2
votes
1answer
45 views

Exploring effect of treatment on count data

I've collected data on animal visitation at four different points in time. The four time points represent the total animal visitations over a three day period, i.e. 3 days of monitoring at four ...
1
vote
1answer
43 views

Count data and heteroscedasticity

Why are count data characterized by heteroscedasticity? If this a violation of the main linear models' assumptions of homoscedasticity, does it mean that in the relevent models for count data ...
4
votes
2answers
117 views

Testing for similarity on count data

Is there a statistical test tat can test for similarity between two data sets on a count data? The only test I can think of doing on a count data is chi squared test and fisher exact test and both ...
18
votes
4answers
591 views

Is this an appropriate method to test for seasonal effects in suicide count data?

I have 17 years (1995 to 2011) of death certificate data related to suicide deaths for a state in the U.S. There is a lot of mythology out there about suicides and the months/seasons, much of it ...
0
votes
0answers
34 views

Estimation of Integer Valued Autoregressive INAR(1) by MLE

Please guide me how to estimate Count data time series Model Integer Valued Autoregressive i.e INAR(1) by Maximum Likelihood Method.
0
votes
0answers
92 views

Zero Inflated Poisson or Negative Binomial Regression model in Panel Data

I am using the Stata version 13.1. My data is count in nature and also it is a balanced panel. However, my data suffers from the problem of excess zeros and also suffers the problem of overdispersion. ...
3
votes
0answers
83 views

Approximate normality of distribution of counts in contigency table

I seem to be struggling with lack of basic understanding of some important concepts. This is a question to the answer of @Glen_b in this post: Warning in R - Chi-squared approximation may be ...
1
vote
1answer
39 views

Searching for signal in a somewhat noisy landscape

I'm trying to implement a system to identify regions of high signal content in the presence of a noisy landscape. By high signal content, I simply mean intensity values significantly above background ...
1
vote
0answers
84 views

Predicted number of events from xtnbreg, fe make no sense

I am trying to compute the number of predicted events from a fixed effects negative binomial regression model in Stata. I run the model first using random effects, then using fixed effects, and ...
3
votes
0answers
77 views

Quasipoisson or negative binomial glmm with differing dispersion by group

I have a set of count data, which look something like this: ...
0
votes
1answer
58 views

What transformation should be carried out if the count is non-integer in poisson glm in r?

My data is like this: person final sex 1 34.20 1 2 2.00 0 3 15.58 0 4 18.00 1 5 50.06 1 I am fitting ...