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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13 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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0answers
15 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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0answers
16 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
17 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}] = ...
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1answer
35 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
29 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 ...
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2answers
90 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 ...
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4answers
494 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 ...
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0answers
23 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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28 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. ...
2
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0answers
47 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
35 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
38 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 ...
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0answers
55 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
40 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
22 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
30 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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0answers
20 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 ...
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3answers
187 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
38 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
34 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
48 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 ...
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3answers
208 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 ...
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0answers
34 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 ...
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0answers
52 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 ...
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0answers
41 views

Poisson regression with underdispersed and truncuated/censored upper bound

I'm analysing data from an experiment in which participants, over a number of trials, were presented with 8 boxes - 7 containing gold coins, and 1 containing a pirate. Their task was to open as many ...
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1answer
58 views

calculation of variance

Hi I have a question regarding calculation of variance of survey results. Consider the following example. If 5 (x) people answered a survey which consists of 3 (y) yes (1) or no (2) questions. You ...
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2answers
114 views

Testing if frequency of event occurrences over week days is uniform

I’m trying to figure out if there’s a calculation that can be done to show you have enough data to draw conclusions on trends within the data set. I have made an observation on a class of equipment ...
3
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2answers
54 views

Can categorical variables be treated as count data?

In a questionnaire study, I asked for the frequency of certain behaviors using a 5-point scale. Originally, I planned to treat it as categorical, however, distribution of the answers (N=1000) turns ...
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0answers
139 views

Negative Binomial Regression model; algorithm did not converge

I am using R to run some negative binomial regression models. For model 1 I have the number of network in-degrees as the dependent variable, and Twitter followers, friends and number of Twitter ...
2
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1answer
21 views

Estimating better performing variation with unkown sample size

Scenario: We are in the app business and trying to optimize for downloads in the app store. Things like the shown screenshots, the text, the icon etc. can be changed and will have an influence on the ...
0
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0answers
9 views

What test to run for one group with two binary categories

I'm not sure what is the appropriate test for this simple question: I have 1858 observations in two different conditions and for each observation there are two possibly outcomes: IN or OUT. My counts ...
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0answers
24 views

Negative Binomial Anscombe Residuals

I need a help :) I'm working on a Generalised Linear Regression model, using the 'so called' NB2 model, in other words I'm using the Negative Binomial regression for count data. I would like to graph ...
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0answers
15 views

Help in determining prediction accuracies over the life of a customer

I have been tasked with determining the accuracy of some data, however my statistical knowledge is weak and I am hoping to be pointed in the proper direction. For a customer, we have a series of ...
1
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1answer
41 views

Which models for suitable for integer values of independent and dependent variables

The data set has independent and dependent measurements that are events, and can be counted. What input / output models are appropriate for integer values? So far I've tried linear regression, and ...
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0answers
15 views

Correlation between offset and predictor in count data

I am fitting a Poisson model that requires an offset term to account for sampling effort. However the offset term is highly correlated with one of the linear predictors that is central to my ...
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0answers
40 views

R implementation of Zeger's parameter-driven (latent process) approach to time series regression with count data

For time series regressions with count data, Poisson-response with log link (i.e. GLM) is widely used. However, such models often suffer from serial correlation. One approach to handle was introduced ...
5
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2answers
67 views

Appropriate method for determining difference between means?

I'm looking at the calling rate of bird species when prey availability is altered. So there are two groups, a control (no manipulation) and experimental group (where prey has been increased). I'm ...
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0answers
19 views

What test should I do to evaluate overlap between two sets of count data

I have one set of data. This set A has about 5000 members and they are divided in 8 subgroups, but each member has also a membership in one out of 24 other groups (let's call these set B). What I want ...
2
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0answers
36 views

Does N-1 correction for Pearson's Chi-Square apply to r x c tables generally?

Campbell (2007) recommended what he called the "N-1" correction for chi-square tests performed on two-by-two contingency tables. He described the correction as: "the K. Pearson chi-squared test ...
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1answer
355 views

How to interpret ANOVA output when comparing two nested mixed-effect models?

I've got two models (all variable are count variables): ...
0
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0answers
27 views

Simulation of CI of amount of values in different intervals by adding noise to original data

I am having a hard time trying to solve this problem, so maybe some of you guys can sort it out. I have a large data set containing a value describing the thermal comfort in buildings called PMV. The ...
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2answers
163 views

Alternative for Fisher's exact test for count data in table bigger than 2x2

I have count data on different languages from comparable corpora. It looks something like this, where the counts give the number of clauses with that particular word order attested in each language ...
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0answers
23 views

Good way to categorize count data?

I want to use some count data to train a classifier. The count data range from 0 to 400 something. There are a bunch of smaller counts (0's and 1's). I wonder what would be a good way to categorize it ...
1
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0answers
148 views

Count data in a Structural Equation Model

I am currently trying to fit a structural equation model (SEM) on a certain dataset using R (lavaan package). Some of the most important variables in my model are count data (abundance of different ...
0
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0answers
19 views

What is the number of “observed data” in a multivariate HMM

I am trying to calculate BIC scores for a couple of models with different states. (See general question 1 and a more specific q2 - no answers in either). I've done my own research a little bit and ...
1
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0answers
22 views

How to compare a one-day count against a historic mean to identify an external change

A few months ago a client's website had some good press and their daily site visits spiked. Now, every time their traffic shows a bump, they think something external has caused it to happen. I'm ...
1
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1answer
187 views

How to compare count of two groups?

I have a two groups of data - 1/ All data and 2/ Selected_season, which is only some subgroup of all data. I want to find out: a/ if proportion of BM, HB, etc. groups is the same in All data and ...
2
votes
2answers
50 views

How to do smoothing of data with low counts?

We are a facing a problem of fluctuating shares for each week for the products we are studying due to low counts. e.g. If we have 4 products and for each one we have say like 5,8,3,6 details and we ...
1
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1answer
95 views

How to model a count dependent variable with upper limitation

I have a dependent variable, which have 0, 1, 2, or 3 for its value. I asked participants to choose three items and coded 1 if it is in a certain category and 0 otherwise. I add the three binary ...