similar to: Maximum likelihood estimation in R with censored Data

Hi, I am trying to get the maximum likelihood estimator for lognormal distribution with censored data;when we have left, interval and right censord. I built my code in R, by writing the deriving of log likelihood function and using newton raphson method but my estimators were too high " overestimation", where the values exceed the 1000 in some runing of my code. is there any one can

Hi , I am trying to get some estimator based on lognormal distribution when we have left,interval, and right censored data. Since, there is now avalible pakage in R can help me in this, I had to write my own code using Newton Raphson method which requires first and second derivative of log likelihood but my problem after runing the code is the estimators were too high. with this email ,I provide

Hello! I have a matrix with data and a column indicating whether it is censored or not. Is there a way to apply weibull and exponential maximum likelihood estimation directly on the censored data, like in the paper: Backtesting Value-at-Risk: A Duration-Based Approach, P Chrisoffersen and D Pelletier (October 2003) page 8? The problem is that if I type out the code as below the likelihood

Dear R users, This is a basic question. I want to fit a Weibull distribution. fitdistr(data, "weibull") works and it is a maximum likelihood fitting. Is it a good method ? Or is it better to write a function for the log-likelihood and the gradient and to use a numerical routine ? Fitdistr works for uncensored data, but what can I use for censored (and uncensored) data ? Thank you

One set of data has censored (less-than detection limits) water chemistry concentrations for 80-100% of all observations. My initial trial-and-error attempts to apply the cenboxplot() method suggests that it has an upper limit to the percentage of censored observations. I do not see this limit in Dennis Helsel's second edition. Has anyone experience plotting censored data and can provide

(1) ...need to speed up a monte-carlo sampling...any suggestions about how I can get R to use all 8 cores of a mac pro would be most useful and very appreciated... (2) spent the last few hours trying to get pnmath to compile under os- x 10.5.4... using gcc version 4.2.1 (Apple Inc. build 5553) as downloaded from CRAN, xcode 3.0... ...xcode 3.1 installed over top of above after

Hello, I have interval censored data, censored between (0, 100). I used the tobit function in the AER package which in turn backs on survreg. Actually I'm struggling with the distribution. Data is asymmetrically distributed, so first choice would be a Weibull distribution. Unfortunately the Weibull doesn't allow for zero values in time data, as it requires x > 0. So I tried the

Hi all, I need to check for a difference between treatment groups in the parameter of the geometric distribution, but with a cut-off (i.e. right censored). In my experiment I stimulated animals to see whether I got a response, and stopped stimulating if the animal responded OR if I had stimulated 10 times. Since the response could only be to a stimulation, the distribution of response times

Hi, Is there a way to make demo() print comments along with the code and output? For example, if I use something like readline("..."), demo prints both readline("...") and ...; as far as I can tell, this is also true of print() and cat(). I just want students to stop and think about every command in my demo scripts. Thanks, Olivia.

install.packages works for Linux because the directory structure is not version dependent, as it is for the Windows download. That should be fixed as soon as my sys admin consents to install R 1.9.0 so we can do the cross compile. Of course, you are right, Martin and Peter, that Zelig should be on CRAN proper. We just need to write a few .Rd files to be compliant with R check, and change our

Hi, I am trying to use boot() to refit an ordinal logit (polr in MASS) model. (A very basic bootstrap which samples from the data frame without replacement and updates the model.) I need to extract two statistics per run (the coefficients and zeta) and I tried concatenating them into a single vector after fitting, but I get the following error: Error in "[<-"(*tmp*, r, ,

Hi, I am working on a package which requires separate documentation (tutorial documentation, really, with a lot of beautifully latexed equations), and does not use R-help. I am trying to make it so that my help function will automatically search R-help if the help topic isn't found in my documentation. The function looks something like this: help.pkg <- function(topic) { #

Hi, I am working on a package which requires separate documentation (tutorial documentation, really, with a lot of beautifully latexed equations), and does not use R-help. I am trying to make it so that my help function will automatically search R-help if the help topic isn't found in my documentation. The function looks something like this: help.pkg <- function(topic) { #

Dear R-experts: I am using survreg() to estimate the parameters of a Weibull density having right-censored observations. Some observations are weighted. To do that I regress the weighed observations against a column of ones. When I enter the data as 37 weighted observations, the parameter estimates are exactly the same as when I enter the data as the corresponding 70 unweighted observations.

Hi, I'm trying remote connection with qemu hypervisor on FSL PPC board. The libvirt server is the PPC board. root at ppc:~# ifconfig eth0 10.193.20.109 root at ppc:~# libvirtd -d root at ppc:~# virsh -c qemu:///system define test.xml root at ppc:~# virsh -c qemu:///system start test root at ppc:~# virsh -c qemu:///system list --all Id Name State

Dear R users, I am new to R. I would like to find *maximum likelihood estimators for psi and alpha* based on the following *log likelihood function*, c is consumption data comprising 148 entries: fn<-function(c,psi,alpha) { s1<-sum(for(i in 1:n){(c[i]-(psi^(-1/alpha)*(lag(c[i],-1))))^2* (lag(c[i],-1)^((-2)*(alpha+1)) )}); s2<- sum(for(m in 1:n){log(lag(c[m],-1)^(((2)*alpha)+2))});

Hi, I used to convert qemu XML to args with libvirt-1.0.3. But it failed to convert with libvirt-1.0.4. # virsh domxml-to-native qemu-argv test.xml >test.sh error: An error occurred, but the cause is unknown Comparing the debug file as below: 1) lbvirt-1.0.3 <cut> 2013-04-09 03:23:47.296+0000: 2669: debug : virEventPollInterruptLocked:716 : Interrupting 2013-04-09 03:23:47.296+0000:

Dear All, I have two questions regarding distribution fitting. I have several datasets, all left-truncated at x=1, that I am attempting to fit distributions to (lognormal, weibull and exponential). I had been using fitdistr in the MASS package as follows: fitdistr<-(x,"weibull") However, this does not take into consideration the truncation at x=1. I read another posting in this

I read through Harrington and Fleming (1982) but it is beyond my statistical comprehension. I have survival data for insects that have a very finite expiration date. I'm trying to test for differences in survival distributions between different groups. I understand that the medical field is most often dealing with censored data and that survival analysis, at least in the package survival,

I am trying to fit a lognormal distribution on interval-censored data. Some of my intervals have a lower bound of zero. Unfortunately, it seems like survreg() cannot deal with lower bounds of zero, despite the fact that plnorm(0)==0 and pnorm(-Inf)==0 are well defined. Below is a short example to reproduce the problem. Does anyone know why survreg() must behave that way? Is there an alternate