Questions tagged [count-data]

Count data are non-negative integers representing whole amounts.

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lme4 mixed model analysis based on sum of count data

I have a dataset with pupils (1000+) that are nested within school classes (100+). Pupils were either in group1 or group2 (different treatments) and had two measurement time points (time0, time2). The ...
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Which regression models are appropriate for (ratios of) two different but dependent counts?

Consider a variable Y which is the ratio of the frequencies of two words/concepty (f,g) in a text: Y = f/g. Since the texts do not have equal length, the denominator when calculating the percentage of ...
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What test can I use to compare count data across groups?

I've conducted an experiment using seeds from several locations to test their viability. For each location, seeds were classed as viable or non-viable, giving me the total amount of viable and non-...
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GLMMs for count data shows significant deviation according to DHARMa diagnostics qqplot

I am making a GLMM to test for various aspects of grooming in primates. I have made 3 different models for the different species. For 1 of the 3 models, I am getting an issue with the qqplot. The data ...
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How to interpret coefficents when you have an offset?

I'm measuring counts of birds as a function of the time (in months) across three parks (NP), as well as the presence of carcasses and season. I'm trying to find out whether the population is ...
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High frequency zero-inflated negative binomial model with Hauck-Donner effect

I have high-frequency (daily) data with overdispersion and a high amount of zeros. I know that a zero-inflated negative binomial is my best option for a model. I am using the library ...
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Special case of comparing poisson-distributed counts

I have count data (microbiology lab work) in which I have a serial 10-fold dilution of cells, and then grow the dilutions in 2 different conditions. For each dilution, I have 24 wells that could 'grow'...
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Statistical test for count data [duplicate]

I'm currently trying to figure out which statistical test to use for my count data, and I'm a little confused on how to go about it. The data that I'm working with consists of number of camera trap ...
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How to specify the formula for a GLM Negative Binomial model in R

I'm looking for some feedback on my approach to predicting a count variable in my dataset. I'm unsure as to whether my approach is sound. My dataset is stored here if anyone is interested. Since my ...
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Model/test to determine whether a trend in abundance over time is significant?

I have population abundance data for a range of years. What I would like to do is test/model the trend in abundance (i.e. count data) over time (i.e. in years), and also see whether the observed trend ...
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Is it wise to use a Generalized Linear Model (GLM) to investigate trends in abundance over time?

Not sure if this would be considered as being a "stupid" question, but I am still very new to statistical analyses. I have population abundance data and I wish to determine whether the trend ...
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1 answer
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Negative binomial not capturing overdispersion in glm model

Following this example, I am fitting a glm model with rstanarm to count data that look like this: The simple specification below runs just fine: ...
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Establish a relationship between calls and sales where calls data is count independent variable

I am trying to model sales of 2020 on calls of 2020 where the values of calls are (0,1,1.5,2,2.5,3,3.5......,19,19.5,20). My lookout is to establish some sort of relationship between the two variables....
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Predicting deterioration of equipment on a production line

Background There is a production line where there are 10 machines that interact with some tools. The process goes as such. Machine makes a product Product is moved into the tool When the product is ...
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Valid model comparison/selection? Poisson, negative binomial, zero-inflated poisson, z-i negative binomial with AIC

I want to model counts of an event in a pre-post design. A sample dataset could look like this: ...
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1 answer
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Count vs. continuous predictors in Poisson regression with offset

I'm having a conceptual problem related to using different types of predictor variables (i.e., count data vs. continuous data) in Poisson regression. My field method was walking transects and counting ...
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calculating ICC manually versus the performance package

I reproduced an example I found on Stackexchange, here, and I failed to get the same ICC using the performance::icc package in R. My reproducible example is below. Can someone explain to me why the ...
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How to identify drivers of a count variable?

I have an app in which users go through a form and select options which represent their views about an event they attended. These options are presented like "tags" that the user can select. ...
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How can I statistically assess directionality for larger tables of count data (eg 2x3, 2x4)?

I have an experiment with 2 dependent variables (each binary decisions) that makes some quite distinct hypothesis about the manipulation. As there are 2 dependent variables, there are 4 outcomes that ...
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Zero Inflated Negative Binomial: model equation and GLM equation

I've fitted a Zero-inflated negative Binomial (with an offset) to a count variable where there is overdispersion and a large frequency of 0's. I've done this with the ...
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2 votes
1 answer
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Should I use a Poisson distribution for count data which appears normally distributed?

I have some count data on woodland species which appears to be fairly normally distributed (See histogram below). I am fitting it as the response variable in a glm with multiple explanatory variables. ...
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Time Series: Predicting daily count sales data of three different products

I have a data set containing historic daily sales of 3 products pasta, nuts and yeast for one year (2020-01-01 - 2020-12-31). Pasta and nuts are from store 1, while yeast is from store 2. The ...
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1 vote
1 answer
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Linear regression with Poisson distributed error term?

I am working on gut microbiome data (counts) and I came across a paper where they are trying to predict bacteria counts in time using a linear regression model with Poisson distributed error term. I ...
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Na/Nan/Inf Error in R While Running a Negative Binomial Model

After running this negative binomial model: ...
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Fisher's exact test on k-mers counting - Bioinformatics

I'm quite new to the bioinformatics field, so I hope I won't make a too stupid question. I'm trying to compare different samples by applying some statistical tests (i.e. Fisher's exact test) to the ...
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Simulating Count Time series in R

I have estimated parameters for count time series a model in r using data: Here is the code: ...
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Meta-analysis of paired count data

I have data from 70 studies reporting number of observed events in two time periods, one before Covid and one during the Covid pandemic. The duration of the timeperiods and the size of the population ...
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What is an appropriate measure or test of reliability (internal consistency) for count data?

Internal consistency is often measured using Cronbach's Alpha which is a correlation based test. However, correlating count data (e.g. Item 1 = 4, Item 2 = 0, Item 3 = 3, etc.) with each other isn't ...
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How to investigate my proposed likelihood ratio test via a simulation study?

I have developed three likelihood ratio tests (LLT) based on three different hypotheses for a certain distribution, say $X.$ I understand how to use it when dealing with real data application. I do ...
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Time series analysis with non-stationary count data (Poisson/Negative binomial models)

I am trying to model the relationship between real-world events and specific features present in tweets related to these events. Whereas my dependent variable (events) is a count variable and its time ...
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chi-square goodness of fit test on count data

I am performing chi-square goodness-of-fit test on a predicted and observed count data. Some observed counts are very low or zero. I have a two part question, - Does r's chisq.test function exclude ...
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How to Assess Multicollinearity for Independent Count and Rate Variables

How do I test an independent variable for multicollinearity if it comes from a Poisson or Negative Binomial distribution? A common approach for testing the multicollinearity of a model's independent ...
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compare whether 3 factors of a categorical variable are distributed differently

For every subject in a study, I have 40 responses that can be: a,b,c. So it would look somthing like sub | trial | resp 1       1        a 1       2        b .... 50   ...
2 votes
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Correct loss function and metric for regression of count data in neural network

I am using a convolutional neural network to predict the number of occurrences of a certain pattern in time series data. Since there might be potentially any count of such patterns in a time series, I ...
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2 answers
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Appropriate visualizations for exploring count data

I am preparing to do a regression model (probably Poisson) where the goal variable is count data (number of times a patient received a blood transfusion). I will have to do variable selection out of ...
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1 answer
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Can very large count outcomes be treated as continuous variables?

I have very little expertise with count outcomes and analysis of them, but I understand that, in general, they cannot be treated as continuous dependent variables for the purpose of analysis due to ...
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Negative Binomial Regression with Moderation Effect

In H1, I predict the positive effect of a program on the consumer spendings. In H3, I want to predict the positive effect of a program on the number of referrals, while also predicting the positive ...
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Interpreting DHARMa residuals for a glmer.nb regression using count data

1 I am modeling overdispersed count data (detection of species) in a GLMM to account for changes in the number of detections of the individual (response variable) to covid period, area (rural vs urban)...
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How to analyse count data

I have count data on bird abundance obtained from 12 locations. I have summed the abundance for each site as I have been sampling each location twice and there is no significant difference between ...
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Comparing multiple proportions with zero/1 values

I have a dataset (see below) where I've located bird nests of five different species over four survey periods. For each bird nest I recorded if these were actively being used or not. I want to compare ...
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Can the offset variable be smaller than the outcome variable in a Poisson model?

I am modeling a number of bags of local crop harvested from a village in a given harvest over time. The village is divided into 48 communities and I have data on the total number of bags of crops from ...
7 votes
1 answer
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Why does log-linear analysis seem to ignore the Poisson regression equidispersion assumption?

As far as I understand it, log-linear analysis is based on the use of a Poisson regression. This is what I understood from various online resources, like this online tutorial or this text whose intro ...
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1 vote
1 answer
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How to interpret an interaction in a negative binomial?

I'm investigating the influence of top management team nationality diversity (TMTdiv, continuous between 0-1) and board nationality diversity (Boarddiv, continuous between 0-1) on firm ...
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Combining results of 2 survey sources

In my study, I have data from 2 survey sources (from 2 groups of people). They are very different from each others. A few major differences: First group did not get paid to answer the survey while ...
1 vote
2 answers
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How can I calculate common digits in daily numbers?

We have daily numbers with 4 digits and 3 digits. These winning numbers often,but not always, have 1 or more digits the same. It would seem there should be a strategy to calculate the percent of time ...
10 votes
2 answers
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Estimating probability of attack in Ukraine, given count data

I was looking at some attack count data in Ukraine for different days. The data is gathered from the ACCLED dataset, and there is a picture below. The picture shows individual attacks, but I can apply ...
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Statistical Analysis on R with Count/Observation Data, multiple explanatory variables [duplicate]

I am running an analysis using R to determine if boat activity impacted shark residence times. I have observation data that includes number of observations within ONE observation event (e.g. number of ...
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Urban Site observation data analysis suggestion

I have conducted site observation at four different locations for a period of 20 mins. (Total of 30 observations for each site). During the site observation, the pedestrian counts, age group and ...
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1 answer
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Confidence interval for multiple samples of ratios of counts (in R)

Data and objective I have count data from two groups, A and B, from across multiple samples. I want to estimate the average ratio of A to B across all samples, along with a confidence interval. Issues ...
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Meta-analysing impact of Covid pandemic on risk for perforated appendicitis

I am analyzing the impact of the change in the management of appendicitis during the covid pandemic. I have paired data from 31 reports comparing the number of operations for perforated and ...
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