search for: zicounts

Displaying 13 results from an estimated 13 matches for "zicounts".

2007 Oct 24
1
Zicounts package
Dear R users, I have been using the zicounts package (verson 1.1.4) in R (version 2.4.1). I have been fitting zero inflated Poisson regressions to model the number of trips made by a household. Whilst I can get the best fit parameter set from zicounts, I can't get the package to return the fitted values for the model. I have attempte...
2007 Aug 13
2
Error message when using zero-inflated count regression model in package zicounts
...s fairly skewed (median = 0, mean = 1.158, 3rd qu. = 1.000). I am attempting to investigate whether plot location (four sites), species (I'm using only the four most common species), or tree dbh has a significant influence on the number of vines per tree. When I attempted to use the zicounts function, R gave me the following error message: > vines.zip<-zicounts(resp=Total.vines~.,x=~Site+Species+DBH,z=~Site +Species+DBH,distrname="ZIP",data=sycamores.1) Error in ifelse(y == 0, 1, y/mu) : dim<- : dims [product 12] do not match the length of object [549] In additi...
2007 Mar 09
1
help with zicounts
Dear UseRs: I have simulated data from a zero-inflated Poisson model, and would like to use a package like zicounts to test my code of fitting the model. My question is: can I use zicounts directly with the following simulated data? Create a sample of n=1000 observations from a ZIP model with no intercept and a single covariate x_{i} which is N(0,1). The logit part is logit(p_{i})=x_{i}*beta with beta=1, and...
2007 Jul 26
1
zeroinfl() or zicounts() error
...: system is computationally singular: reciprocal condition number = 1.91306e-34 When I include "BuildingArea", I get this error: Error in optim(fn = loglikfun, par = c(start$count, start$zero, if (dist == : non-finite finite-difference value [2] I tried fitting the models using zicounts in the zicounts library as well and had the same difficulty. When I include "PopulationDensity", it runs, but outputs only the parameter estimates, not the standard errors or p-values (those have NaN). When I include "BuildingArea", I get this error: Error in solve.default(z0...
2007 Aug 21
2
Optimization problem
...0 0 0 0 0 1 0 0 0 0 ... $ Scars : int 0 0 0 0 0 5 0 4 5 5 ... $ Lar : int 15 0 3 0 0 0 1 0 0 3 ... $ Mass : num 13.9 15.6 16.4 16.6 17.5 ... $ Lacfac : Factor w/ 2 levels "0","1": 1 1 1 1 1 2 1 1 1 1 ... The syntax I used to create the model is: zinb.zc <- zicounts(resp=Scars~.,x =~Location + Lar + Mass + Lar:Mass + Location:Mass,z =~Location + Lar + Mass + Lar:Mass + Location:Mass, data=alan) The error given is: Error in optim(par = parm, fn = neg.like, gr = neg.grad, hessian = TRUE, : non-finite value supplied by optim In addition: Warning messa...
2005 May 17
1
Vuong test
Hi, I have two questions. First, I'd like to compare a ZINB model to a negativ binomial model with the Vuong test, but I can't find how to performe it from the zicount package. Does a programm exist to do it ? Second, I'd like to know in which cases we have to use a double hurdle model instead of a zero inflated model. Many thanks, St??phanie Payet REES France R??seau
2007 Aug 22
1
All subsets regression
Hey folks, I'm trying to do all subsets on a zero-inflated poisson regression. I'm aware of the leaps and regsubsets functions but I don't know if they work for ZIP regressions or how the syntax fits in for them. Can anyone help? The model syntax is: > zip.zc <- zicounts(resp=Scars~.,x=~Location + Lar + Mass + Lac + Lar:Mass + Location:Mass, data = alan2, distr="ZIP") Many thanks Alan Harrison Quercus Queen's University Belfast MBC, 97 Lisburn Road Belfast BT9 7BL T: 02890 972219 M: 07798615682 [[alternative HTML version deleted]]
2005 Apr 13
0
Summary: GLMMs: Negative Binomial family in R
.... ***************************************** Check out glm.nb() from package MASS fits negative binomial GLMs. ***************************************** For known theta, you can plug negative.binomial(theta) into glmmPQL() for example. (Both functions are also available in MASS.) Look at package zicounts for zero-inflated Poisson and NB models. For these models, there is also code available at http://pscl.stanford.edu/content.html which also hosts code for hurdle models. ***************************************** Consider using the function supplied in the post: https://stat.ethz.ch/pipermail/r-h...
2005 May 04
1
Double hurdle model in R
I am interested in utilizing this so called "double hurdle" model in my study. We can write the model in the following way: if (z'a + u > 0 & x'b + e > 0) y = x'b + e, else y = 0 In the model, consumption y is the (left-) censored dependent variable. e and u are the normally distributed error terms. z'a is the participation equation and x'b is the
2007 Aug 02
0
Package portability issues
...on error message is An integer constant expression is required within the array subscript operator. Here is an example: double data[(*nrow)+2*env][(*ncol)+2*env]; This affects at least packages GammaTest MCMCpack MasterBayes clusterSim dprep edci epsi knnFinder pbatR rmetasim zicounts 2) Including C header files is fraught with difficulties. Unfortunately that includes the R header files, because they in turn include system C headers. The checking of which features were available was done using the C compiler with particular flags, and glibc has a habit of hiding features...
2005 Apr 05
2
GLMs: Negative Binomial family in R?
Greetings R Users! I have a data set of count responses for which I have made repeated observations on the experimental units (stream reaches) over two air photo dates, hence the mixed effect. I have been using Dr. Jim Lindsey's GLMM function found in his "repeated" measures package with the "poisson" family. My problem though is that I don't think the poisson
2007 Aug 16
2
Newbie
...29/05/2007 Tollymore 1 T11 FALSE 0 A 1 0 0 0 2 0 3 0 16.30 104 29/05/2007 Tollymore 1 T28 FALSE 0 A 0 0 0 0 0 0 0 0 14.49 And here is the syntax is used to run the ZINB with the error message, any help greatly appreciated. > zinb.zc<- zicounts(resp=Scars~.,x=~Age,z=~Age, data=alan) Error in solve.default(z0$hessian) : system is computationally singular: reciprocal condition number = 3.44599e-18 Cheers Alan Alan Harrison Quercus Queen's University Belfast MBC, 97 Lisburn Road Belfast BT9 7BL T: 02890 972219 M: 07798615682 [[a...
2007 Mar 26
1
Problem in loading all packages all at once
...;,"vegan","verification","verify","vioplot","VLMC","wavelets","wave slim","wavethresh","wccsom","WhatIf") TEMP <- c(TEMP,"wle","XML","xtable","Zelig","zicounts","zoo") #TEMP <- c(TEMP,"runfirst") #TEMP <- c(TEMP,"runfirst","base","datasets", "utils", "grDevices", "graphics","stats","methods","lmtest") print ("MODIFIED R_DEFAULT_P...