similar to: Poisson regression in R

Hello, I am fitting a Poisson mixed effects model. I have the number of eggs (Eggs) laid by a quail and looking at the effect of dosage of a chemical (Dose) in the study. I have counts of eggs laid by week of the study, so I am including the week number (Week) as a random effect. I'm using the lme4 package. I have, > mod1 <- lmer(Eggs~Dose + (1|Week),family=poisson) >

Hello all, I am Xiongqing Zhang, come from Beijing of China. I know you from the web site: http://finzi.psych.upenn.edu/Rhelp08/2008-February/154627.html. I am not very clear about the R-project software. But I want to estimate the parameters and errors of zero-inflation poisson model. Can?you help me? Data is in the attachement. Thank you. I will be very appreciated if you can help me. Best

Quasi-Poisson regression - using parameter estimates for QAICc Hello, I am using lmer (package lme4), for a GLMM, where I am modeling overdispered data with 1 random effect and several fixed effects. I want to use QAICc for my model selection, however I have 2 concerns 1) I don't know how to properly estimate the overdispersion parameter (c_hat), which is needed to calculate QAICc. I

Dear list, I'm trying to fit a glm model using family=poisson(link = "identity"). The problem is that the glm function fits a model with a negative intercept, which sounds like a nonsense to me, being the response a Poisson variable. >From a previous discussion on this list I've understood that the glm function uses IRLS for the fitting without any constraint so it is

Hi there, I have relative abundance data for 13 mammal species that I collected at various sites that ranged in road density. I'm trying to determine the effect of road density on animal abundance across body sizes. For most species, I have data that was collected in one year but for a few species I have two years of complete data, and would like to use both. Since I have count data, I'm

Hi All, I am using em() function to estimate a poisson-gaussian process from a univariate one dimension time series, but not sure how to do. In the help manual, it specify that in "pro" of the argument "parameter", if the model includes a Poisson term for noise, there should be one more mixing proportion than the number of Gaussian components. But in the example, the parameter

Dear list, I am wondering whether R allows to perform a Poisson regression on counting data which include censored observations, that is, observations of the form "2 events or more" or "less than 2 events" or even "1 or 2 events". Can anyone give me a hint whether this is already possible and how to do it? Data of the form (obstime is the observation time,

Dear all, I'd like to measure the prediction accuracy of a model I have derived from poisson regression. Can somebody help me with suggesting a good approach please? Thanks very much in advance. Best wishes, Des [[alternative HTML version deleted]]

Hello, I'm looking for a dataset for Quasipoisson regression. The result must be significantly different from the classic poisson regression. You can help me? Please It is for my last university exam Thanks a lot -- View this message in context: http://r.789695.n4.nabble.com/Dataset-Quasi-Poisson-tp3533060p3533060.html Sent from the R help mailing list archive at Nabble.com.

Hi. I would like to know if is it possible to estimate zero-truncated count models with robust standard errors in R. In Stata that is possible. I already made some searches and attempts but not obtained it. In R I made the estimation of the truncated poisson by the vglm command of VGAM package . -- View this message in context:

I am wondering if stepAIC in the MASS library may be used for model selection in an overdispersed Poisson situation. What I thought of doing was to get an estimate of the overdispersion parameter phi from fitting a model with all or most of the available predictors (we have a large number of observations so this should not be problematical) and then use stepAIC with scale = phi. Should this

Hi ! I have been using BMA (bayesian model Averaing) package for modeling purposes, but was faced with a problem of incorporating offset term in the Poisson regression of disease rates. It looks like bic.glm does not accept offset keyword like glm ? Any ways to solve the problem using wt option in BMA? Janne Pitk?niemi -- Department of Public Health P.O.Box 41 (Mannerheimintie 172) 00014

Hola! Anybody knows if there exists somewhere in R some implementation of robust Poisson regression, where robust is taken in the sense as usen in rlm(MASS). I found something in the package wle, but only for the Poisson distribution, not for regression. For the moment I try to use linear models with the square-root transformation, and rlm. Kjetil -- Kjetil Halvorsen. Peace is the most

Dear Listers, I have a general statistical question. Are hurdle logit-poisson model and posson model nested? Thank you so much?

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Dear all I want to simulate a stochastic jump variance process where N is Bernoulli with intensity lambda0 + lambda1*Vt. lambda0 is constant and lambda1 can be interpreted as a regression coefficient on the current variance level Vt. J is a scaling factor How can I rewrite this avoiding the loop structure which is very time-consuming for long simulations? for (i in 1:N){ ... N <- rbinom(n=1,

Hello, I'm fitting poisson regression to mortality data and wish to stratify by age. Is there any way to perform this stratification and use the glm function in R? Thanks, Hannah Murdoch

Hi all, I'm here again with my newbies questions :( I have a simple example: count of slugs in two fields. I need to make a barplot with mean and SE of mean. So I have: The mean: > tapply(slugs,field,mean) Nursery Rookery 1.275 2.275 The SE: > tapply(slugs,field,sd)/sqrt(tapply(slugs,field,length)) Nursery Rookery 0.3651264 0.3508004 If the data has been normally

for a silly question, wondering how to test fit with the one sample as follow. I have read _fitting distributions with R_, but that doesn't answer my specific question. inclined to use Kolmogorov-Smirnov D, and its associative p value. much appreciation! X20.001 232 93 84 185 336 417 228 199 2110 1411 612 1913 1314 3015

Hello! Anyone can help me to know how to do a bootstrap evaluation analysis to a GLM with family=Poisson? I have some R codes but they were coded only for family=binomial... thanks a lot Joana Vicente .?. CIBIO - Centro de Investiga??o em Biodiversidade e Recursos Gen?ticos. Faculdade de Ci?ncias do Porto Departamento de Bot?nica -Edif?cio FC4 Rua Do Campo Alegre, S/N 4169-007 Porto - Portugal