# Tagged Questions

70 views

### Poisson or binomial regression?

I have a binary response variable (it is a presence/absence variable) and a ordinal discrete predictor: ...
33 views

### Count data with continuous variables

Let's assume one has looked at the occurence of a plant species at different altitude, different temperature and environment. Here are its data: ...
36 views

### Getting started with VGAM::vglm

Trying to fit a zero-inflated Poisson model, I have trouble to understand the parameters to the vglm function in VGAM. As an ...
91 views

### GLM experimental design issues for count data in landscape experiment

I am analyzing bird count data from surveys conducted each week (from Nov-April, when bird foraging most active near breeding cycle) for 6 years in 9 large experimental plots that are split amongst 3 ...
726 views

### What advantages does Poisson regression have over linear regression in this case?

I have been given a data set that contains the number of awards earned by students at one high school where predictors of the number of awards earned include the type of program in which the student ...
439 views

### GLM vs square root data transformation

I am currently analysing some pretty awful/awkward data on the abundance of fish under three different "Hydro-Regimes" (5 abundance measurements for each regime - Short/Medium/Long). The current ...
444 views

### Count explanatory variable, ratio dependent variable

I am having a little trouble coming up with a way of analyzing my data. If there is a short answer (i.e., "use logistic regression, dummy") you can just post that and I'll do some digging on my own - ...
377 views

### Best analysis for count data as response variable

I want to know what is the best way to analyze a data set where my response variable is count data and my explanatory variables are continuous variables. All my variables are not normally distributed. ...
1k views

### Why is the square root transformation recommended for count data?

It is often recommended to take the square root when you have count data. (For some examples on CV, see @HarveyMotulsky's answer here, or @whuber's answer here.) On the other hand, when fitting a ...
766 views

### Does using count data as independent variable violate any of GLM assumptions?

I would like to employ count data as covariates while fitting a logistic regression model. My question is: Do I violate any assumption of the logistic (and, more in general, of the generalized ...
326 views

### Can I put Log(Y) as a dependent variable in a count data model

I have count data passenger as Y. The data look like this, as many of the values are 1 (about 18%.) Does it make sense that I take a log of it, and take it as a dependent variable in a generalized ...
670 views

### How to get standard errors from R zero-inflated count data regression?

The following code PredictNew <- predict (glm.fit, newdata = Predict, X1 =X1, Y1= Y1, type = "response", se.fit = TRUE) produces a ...
712 views

### GLM model validation

When performing model validation and we are dropping the least significant explanatory variables until we find the optimum model where all remaining variables are significant, how does one go about ...
278 views

### Generalized linear models dispersion analysis

I was wondering, in relation to model selection for some count data I am looking at using poisson GLMs, would a high residual deviance (measure of dispersion) warrant switching to a quasi-poisson ...
243 views

### Help with R Zeroinfl model

I am carrying out a zero-inflated negative binomial GLM on some insect count data in R. My problem is how to get R to read my species data as one stacked column so as to preserve the zero inflation. ...
I'm interested in plotting the estimator of the standard deviation in a Poisson regression. The variance is $Var(y)=\phi⋅V(\mu)$ where $\phi=1$ and $V(\mu)=\mu$. So the variance should be ...