poisson regression

Code for GLM Poisson regression (R): library(datasets) mydata <- warpbreaks poisson_mod <- glm(breaks ~ wool + tension, mydata, family = poisson()) Gives: Call: glm(formula = breaks ~ wool + tension, family = poisson(link = "log"), data = mydata) Coefficients: (Intercept) woolB...

Let's assume I am working with this dataset on R: n <- 40 x1 <- rnorm(n, mean=3, sd=1) x2 <- rnorm(n, mean=4, sd=1.25) y <- 2*x1 + 3*x2 + rnorm(n, mean=2, sd=1) mydata <- data.frame(x1, x2, y) I cannot understand how Poisson regression works in R, I would assume that the following are...

I have count data, some of which forms an exponential decay type distribution and other data sets which are log normal. They are time series and I’m looking to create autoregressive models using first or second order lags. I have a couple of questions which are follows Is normalising the...

Dear Community, Hopefully, an easy question to answer! Thanks for picking up this thread. I'm doing an evaluation on whether the use of a digital health tool (MyHealth app) changes the utilisation of healthcare services and am stumped on how to do the analysis. We have 4 groups, based on usage...

Hello I want to ask you, before to making a regression should we understand which distribution follow the datas? Let's take an example: if the data have a poisson distribution, then I will run a Poisson regression? If the data follow a gaussian then one should use...

I was reading a paper on Bootstrapping with models for count data. (Page 1170) www.researchgate.net/publication/51738951_Bootstrapping_with_Models_for_Count_Data or www.ncbi.nlm.nih.gov/pubmed/22023684 On the paper the author uses the conventional MLE to fit Poisson...

Hello, I am not sure how to calculate age-adjusted incidence rates using poisson regression. I am comparing injuries for children at two schools, offset by child-days in school and would like to adjust for age. I ran the following model: poisson injuries school i.age, offset(childdays) I...

Using this example (see below) could someone please tell me what the 'e' symbol stands for and how one would work out the expected values manually. 'log(λi) = 1.65 + 0.43 × xi where xi = 1 for a female, and xi = 0 for a male. Poisson Regression Using this example, we see that for a...

Hi, if in regression models homogeneity is violated, the variance can in principle depend on both: Predictor and outcome variable(s). In case of a dependency on categorical or continuous predictor variables, there are many ways to model different dependencies, e.g. using GLS models. In...

Hi, I've data set collected from 700 sheep farms from 5 regions of England (north, south, East, West, Central). The aim is find out if climate variables (maximum temperature, minimum temperature, rainfall) are predictors for animal disease in the regions, so the outcome variable (y) = number of...

Hi, does somebody know why the log-link function is always assumed to be the "standard" link function in Poisson models? E.g. regarding count data (such as numbers of individuals), under which circumstances does it make sense to assume that the response variable increases exponentially with a...

Trying to figure out how best to carry out this analysis... So essentially I have four different species of Deer mice, infected with a high, medium, or low dose of parasite eggs. After euthanasia, I recovered larvae from different tissues of each mouse to compare differences in numbers recovered...

I work for a community group restoring beaches. We've done some preliminary investigation of the vegetation along a shoreline to compare against regional mapping. I have a basic knowledge of statistics but could use some help. 10x100m of shoreline have been sampled to determine dominant...

I have attached an image of an equation of Poisson Regression that i am working on for my data analysis project. I want to understand it a bit as i am new to stats. can anyone tell me whats that Capital 'T' symbol in power of w1 and w2 means? And can anyone guide me to coding this equation in...

I have attached an image of an equation of Poisson Regression that i am working on. I want to understand it a bit as i am new to stats. can anyone tell me whats that Capital 'T' symbol in power of w1 and w2 means? And can anyone guide me to coding this equation in Matlab? Thanks in advance...

Hello everyone. New member, hoping I will be able to contribute and help out! I have been working on this for about 5 days, and gotten to the point where my brain is going in circles. Hopefully you can help me understand what type of analysis this requires. I am conducting what should be...

This is more of a general stats question regarding the best procedure to answer my question of interest. I started to address it using poisson regression in proc GLIMMIX (SAS), but now am unsure about this decision. Experimental Design: I sampled shrubs (stem counts by species) in quadrats...

I am investigating the factors that influence the bycatch of dolphins using a poisson GLM. My response variable is bycatch rate per unit effort and varies from 0 to 0.125. However, my response is very zero-inflated (2304 of 2436 observations are zero). I have three response variables (two...

Hello to everyone!:):) We need some help for a Poisson Regression: Our problem is to determine if there is a relationship between the return on equity of firms (ROE) and the presence (numbers of indicators used) (Y) of a specific type of indicator show in the annual report. At the beginning we...

Thanks in advance for any assistance you have to offer. I'm working with a Poisson model of weighted survey data. My outcome is ACCESS to a weapon (0/1). I have several predictors, including GENDER (0 female /1 male) and a RISK category (0 = no mental health risk factors / 1 = intermediate...