Questions tagged [count-data]
Count data are non-negative integers representing whole amounts.
993 questions
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Modelling counts of a non-exclusive categorical outcome
I have been asked to do a sample size calculation for a survey question of the following form.
Which of the following factors would influence your decision about x (indicate no more than 3)?
Option A
...
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100
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Using glmmTMB for testing effect on total abundance data?
I have count data captured across multiple years and sites. I measured the total abundance for each sampling period, and wanted to determine if there is any significant effect due to temperature ...
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Why/when will negative binomial regression flip the sign of the effect from analogous Poisson regression, after covariate adjustment
First, to be clear, the issue mentioned in the title does not happen often and, in every parametric simulation I've tried, both NB and Poisson produce similar estimates, regardless of the type of ...
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Relative abundance square root transformation PCA- do i have to re-normalise after removing spp <2%?
I have calculated relative abundance of species count data. I then removed the species <2%. I want to transform these data using the square root method to reduce the dominance of some species ...
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How to model Endogeneity in a Zero-Inflated process
I have a multivariate dataset consisting of household level variables such as education, location of the household, occupation, income, consumption etc. The regressand variable is number of social ...
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Is hurdle GAM analysis appropriate for this data?
I have a very small dataset of seabird count data (12 observations/28 samples prions, 22/28 shearwaters, 12/22 storm petrels) and am interested in the association of these taxa and zooplankton ...
- 41
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2
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159
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Correlation of multi-dimensional data
I did an experiment where I asked 18 people to read 12 pieces of shorts text. After they read each text, I asked them to rate how much they enjoyed of the text, and wrote down how their blink rate ...
- 403
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Estimating Confidence or Prediction Intervals for the Total Number of Predicted Events in a Population
I have strata-specific event rates from Population A and have applied them to the corresponding strata in Population B to estimate the number of predicted events. After summing these predicted events ...
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Equivalence test for right-censored count data
How would I perform equivalence tests for right-censored count data? The outcome of interest is total seizures per a time period. However, the equipment used to record seizures stops counting at 40. ...
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Is Poisson regression the default model for count data without overdispersion? [duplicate]
The Poisson model has been commonly used in research to model count data, however when over-dispersion is present, other models are used instead (NB, Quasi-Poisson, for instance). In the event that ...
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Finding outliers in mostly zero data
Background
I'm working on an algorithm to find a short pieces of DNA sequence in a long DNA sequence. I won't go in detail of how it actually works, but let me more formally state it to provide ...
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Statistical test for count values
I have 4 stories that I have the word count and the count for how many plural words are in each:
Story
Num Words
Plurals
1
356
45
2
273
23
3
303
28
4
289
42
I am wondering if it is possible to do a ...
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Selecting statistical test for significant difference between groups from count data with zero values
I wish test significant difference between groups from count data with zero values. I only want to compare groups with the same color (grey, yellow and blue). Some groups have only zero values which ...
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When to use negative binomial and Poisson regression
When would one use a negative binomial regression and when would one use Poisson regression with respect to the mean and variance?
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Using GAM to investigate the within-subject variation between several periods
my research question is to analyse intra-individual (within-subject) heterogeneity in contact patterns and identify determinants of stable contact behaviour before and during the lockdown. Since the ...
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Are these the correct statistical tests to use for my data? Count data for 9 behaviours in 3 age groups
I was hoping you would be able to help me double check if I am using the right tests.
I performed focal studies on 36 deer collecting both the frequency and cumulative time expressed (in seconds) for ...
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Standard negative binomial regression when counts are mainly zeros?
This question must have been asked many times before but I can't find an answer.
I'm getting very confused about when to use a zero-inflated negative binomial regression vs standard negative binomial ...
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Can I include a variable related to the outcome variable into statistical analysis?
My research question is about the contact patterns during the pandemic and what characteristics of people who contacted more person during the national lock down.
The outcome variable is a variable ...
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Negative log-likelihood, high BIC, high R-squared, low error, using a difference-in-differences (DiD) methodology [closed]
I am trying to see the impact of Brexit on UK imports. My dependent variable are EU exports to the rest of world. I have monthly data from 2013 to 2023, also data is in billions of GBP.
When I do ...
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1
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90
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Underdispersion handled with negative binomial distribution? [duplicate]
To get a more flexible model than Poisson regression, one can choose the negative binomial distribution instead for modeling with $E[y] = \mu$ and $Var(y) = \mu + \frac{1}{ \theta} \mu^2$. As a ...
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dispersion of a negative binomial model
In R's, glm.nb summary, it says dispersion parameter $\phi$ is set to 1. When the model is
$Y \sim \text{Negbin}(\mu,\theta)$
where $E(Y)=\mu$ and $V(Y)=\mu+\mu^2/\...
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Count data with time-varying covariates
One way to model count data is to simply count up the number of events as the outcome with an offset of observation time if this varies between people. I presume it's also possible to model count data ...
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How can I justify using counts plus offset in a Poisson or NB model instead of "percent of total"?
I have count data that is part of a whole. It's not compositional, because the other parts of the whole aren't of interest. I could analyze it as a "percent", but I would rather do it as ...
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Difference between zero-inflated model and zero-altered model
Could someone explain what assumptions I am making (perhaps implicitly) when I specify family = nbinom2() versus ...
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