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 ...

learn more… | top users | synonyms

0
votes
0answers
19 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 ...
1
vote
1answer
32 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
votes
0answers
14 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
votes
0answers
11 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
14 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
45 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
votes
0answers
11 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
votes
0answers
21 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
votes
0answers
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: ...
0
votes
0answers
23 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
vote
0answers
21 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
21 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
36 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 ...
0
votes
1answer
34 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
100 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 ...
17
votes
4answers
522 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
24 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
44 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
votes
0answers
61 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
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
vote
0answers
51 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
61 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
42 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 ...
0
votes
0answers
24 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
votes
1answer
31 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 ...
0
votes
0answers
21 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
votes
3answers
192 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
votes
1answer
43 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. ...
1
vote
1answer
38 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 ...
0
votes
0answers
58 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
votes
3answers
214 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
vote
0answers
35 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
vote
0answers
56 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 ...
1
vote
0answers
51 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 ...
1
vote
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 ...
4
votes
2answers
135 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
votes
2answers
58 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 ...
0
votes
0answers
164 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
votes
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
votes
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 ...
1
vote
0answers
30 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 ...
1
vote
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
vote
1answer
46 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 ...
1
vote
0answers
16 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 ...
0
votes
0answers
45 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
votes
2answers
73 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 ...
0
votes
0answers
21 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
votes
0answers
42 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 ...
1
vote
1answer
474 views

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

I've got two models (all variable are count variables): ...
0
votes
0answers
29 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 ...