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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24 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 ...
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1answer
24 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). ...
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50 views
+50

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 ...
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1answer
69 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 ...
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12 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 ...
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0answers
24 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 ...
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1answer
48 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 ...
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2answers
106 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
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2answers
51 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 ...
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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 ...
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1answer
415 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 ...
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22 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.
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1answer
261 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 ...
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2answers
25 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 ...
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27 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 ...
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1answer
26 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 ...
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0answers
41 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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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
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1answer
43 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 ...
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20 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 ...
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0answers
33 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 ...
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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 ...
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0answers
59 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 ...
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0answers
12 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 ...
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46 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 ...
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14 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: ...
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46 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 ...
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30 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
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0answers
23 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
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1answer
43 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 ...
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1answer
40 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
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2answers
112 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
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4answers
575 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
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0answers
29 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.
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77 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. ...
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76 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 ...
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1answer
37 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
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0answers
75 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
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0answers
73 views

Quasipoisson or negative binomial glmm with differing dispersion by group

I have a set of count data, which look something like this: ...
0
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1answer
56 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 ...
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0answers
26 views

Correlation to use for non-scale data( counts)

In our college we run some extra non-required sessions that we hope help the students. To decide whether they help, I wanted to correlate the number of sessions attended with the cumulative gpa of ...
2
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1answer
37 views

Suggested method for estimating door counter stats when data is lost

I'm wondering if you have any advice about a methodology to use to estimate "door counter" stats (i.e., an automated count of visitors to our organisation, based on "break beam" door counters ...
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23 views

Which means difference test to use?

Currently, my data is count data and I am analyzing it in Proc Glimmix in SAS. My data focuses on how many times birds from two treatments performed stand, sit, forage, ect.... So it basically looks ...
3
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3answers
209 views

How can you tell if a yearly increase in population is statistically significant?

I have daily data for two years consisting of "number of sightings" each day. Is there a way for me to test whether the data for year 2 is "significantly" higher than the first year? I know the ...
2
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1answer
47 views

Can I use glm with Poisson family if counts data are treated as density?

Imagine you have data of birds counted in an area - let's say, you count 18 birds in a surveyed area of 1,3 km^2. Imagine you relate this counts to 1km^2, so that you have 13.9 parrots per km^2. ...
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1answer
51 views

How to correlate count variables that are nested / non-independent?

Above is a snapshot of a subset of a larger dataset, N=61. Group is the group number, Iterations is indicating the ...
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0answers
77 views

Modelling count data: mean-variance relationship

I have fit a poisson, quasi poisson, and negative binomial model to some count data. To ensure that I have valid models, I am checking that the following assumptions are satisfied: No ...
7
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3answers
231 views

Modelling count data where offset variable is 0 for some observations

I'm trying to help a student of a colleague. The student observed and counted bird behaviour (number of calls) in an experimental setup. The number of calls attributable to a specific observed bird ...
1
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0answers
37 views

Which significance test can be used in this instance? - paired, non-normal means

I have a data set of behaviours for a herd of captive elephants which I have attempted to quantify to compare for statistical significance, i.e., if a behaviour is performed once during an observation ...
1
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0answers
57 views

Count Panel Data Event Study

Can anyone suggest a lecture/paper/textbook that covers an event study (eg. exogenous policy change) using count time-series (or penal) data? Or alternatively, just a general guideline as to what ...