poisson regression

  1. PB_1989

    Desperate for help => Poisson regression or simple non-parametric test?

    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...
  2. L

    Before to making a regression

    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...
  3. G

    How is simulation used to check differences of regression techniques.

    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...
  4. H

    Age Adjusted Incidence Rates Using Poisson Regression

    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...
  5. S

    'e' in expected values in Poisson

    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...
  6. M

    Violating Homogeneity

    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...
  7. J

    Statistics for regional disease risk factors

    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...
  8. M

    Appropriate link-function in a Poisson Model

    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...
  9. Z

    Kruskal-Wallis or Poisson regression for parasite count data?

    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...
  10. M

    Which test - most frequently observed species - chi-square, nonparametric or poisson?

    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...
  11. R

    Help with a Poisson Regression Equation

    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...
  12. R

    Help with a Poisson Regression Equation

    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...
  13. B

    Overthinking a 'simple' count variable analysis over time

    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...
  14. M

    Is poisson regression appropriate?

    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...
  15. P

    Bycatch of dolphins data, zero inflated and under-dispersed - what next?

    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...
  16. E

    Poisson regression

    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...
  17. S

    Help with categorical interaction terms in Poisson model

    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...
  18. D

    Can anyone explain Poisson regression for doing time trend?

    It would be a big help if someone could give a practical example (by hand) how Poisson regression is used to calculate a time trend line, and calculate a confidence interval for whether there is a trend. Here is some sample data if you would like (Texas viral hepatitis deaths): Year, Events...
  19. P

    Accounting for demographics when outcome is rates

    Hello, I've been reading some public health papers and they account for demographic factors such as age, gender, and race in regression models (poisson/negative binomial) where the outcome is daily/monthly rates. Considering that the demographic factors are at the individual level and rates...
  20. J

    best regression for slaughterhouse variable?

    I'd like to know how several variables are related to the number of small-scale slaughterhouses at the county level throughout the US. There are over 3000 observations. By far, most counties vary between 0-2, but there is a small handful of higher population areas with many more. LA is the...