search for: cder

...far, I have been computing matrices for each parameter (given by par[index]) analytically, using the following kmatder<- function(x, par, index) { ## x: n*m matrix ## par: vector of parameters, m=length(par)=ncol(x) ## compute matrix of partial derivatives wrt parameter par[index]: Cder = d C/d par[index] theta<-1 eta<-par n<-nrow(x) Cder<-matrix(0,n,n) for (i in 1:n) { for (j in i:n) { Cder[i,j]<-(-0.5*((x[i,index]-x[j,index])^2))*theta*exp(-0.5* sum(eta*(x[i,]-x[j,])^2)) } } Cder<-0.5*(Cder+t(Cder))...

I would like to use R for submissions to FDA/CDRH (the medical device company I work for currently uses only SAS). Previous postings to the list regarding R and 21 CFR 11 compliance have been very helpful. However, reluctance to using open source software for statistical analyses and reporting remains high here at my company. Has anyone used R for an official submission to FDA/CDRH? It would

...39;s acceptance in this domain. At the Joint Statistical Meetings in 2006, Sue Bell from the FDA spoke during a session with a presentation entitled Times 'R' A Changing: FDA Perspectives on Use of "Open Source". A copy of this presentation is available here: http://www.fda.gov/cder/Offices/Biostatistics/Bell.pdf In 2007, during an FDA committee meeting reviewing the safety profile of Avandia (Rosiglitazone), the internal FDA meta-analysis performed by Joy Mele, the FDA statistician, was done using R. A copy of this presentation is available here: http://www.fda.gov/ohrms/do...

Hi. I have a problem that I can't seem to find an optimal way of solving other than by doing things manually. I'm trying to subset a data frame by the number of observations that occurred at a given row but want to take into account the number of observations of preceding rows. Here's an example. I'm looking at intervals of data [10,20), [10, 30), ....., [10,120) which contain a

Hi all there Can some one clarify me on this issue, features wise which is better R or SAS, leaving the commerical aspect associated with it. I suppose there are few people who have worked on both R and SAS and wish they would be able to help me in deciding on this. THank you for the help --------------------------------- [[alternative HTML version deleted]]

Hi. After some time, my collegues at the Food and Drug Adminstration have finally acknowledged R as a powerful statistical computing environment. However, in order to comply with the Office of Information and Technology standards there are a couple of questions about whether R could interfere with other software. As I'm more of a driver of the R software and not a mechanic, I was hoping for