Dear Sir, Thank you for your response. You were correct, I had 1 linearly dependent column. I have solved this problem and now the rank of 'covaeb' is 17 (qr(covaeb)$rank = 17). However, I still get the same error message when I use covaeb in the 'crr' function.
> fit=crr(snearmb$with.Withtime,csaeb,covaeb,failcode=2,cencode=0) 8 cases omitted due to missing values Error in drop(.Call("La_dgesv", a, as.matrix(b), tol, PACKAGE = "base")) : system is computationally singular: reciprocal condition number = 3.45905e-25 Are there any other reasons why this may be happening? Thank you, Laura 2009/6/25 Ravi Varadhan <rvarad...@jhmi.edu>: > This means that your design matrix or model matrix is rank deficient, i.e it > does not have linearly independent columns. Your predictors are collinear! > > > Just take your design matrices "covaea" or "covaeb" with 17 predcitors and > compute their rank or try to invert them. You will see the problem. > > Ravi. > > ---------------------------------------------------------------------------- > ------- > > Ravi Varadhan, Ph.D. > > Assistant Professor, The Center on Aging and Health > > Division of Geriatric Medicine and Gerontology > > Johns Hopkins University > > Ph: (410) 502-2619 > > Fax: (410) 614-9625 > > Email: rvarad...@jhmi.edu > > Webpage: > http://www.jhsph.edu/agingandhealth/People/Faculty_personal_pages/Varadhan.h > tml > > > > ---------------------------------------------------------------------------- > -------- > > > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On > Behalf Of Laura Bonnett > Sent: Thursday, June 25, 2009 11:39 AM > To: r-help@r-project.org > Subject: [R] crr - computationally singular > > Dear R-help, > > I'm very sorry to ask 2 questions in a week. I am using the package 'crr' > and it does exactly what I need it to when I use the dataset a. > However, when I use dataset b I get the following error message: > Error in drop(.Call("La_dgesv", a, as.matrix(b), tol, PACKAGE = "base")) : > system is computationally singular: reciprocal condition number = > 1.28654e-24 > > This is obviously as a result of a problem with the data but apart from > dataset a having 1674 rows and dataset b having 701 rows there is really no > difference between them. > > The code I am using is as follows where covaea and covaeb are matrices of > covarites, all coded as binary variables. > In case a: >> covaea <- >> cbind(sexa,fsha,fdra,nsigna,eega,th1a,th2a,stype1a,stype2a,stype3a,pgu >> 1a,pgu2a,log(agea),firstinta/1000,totsezbasea) >> fita <- crr(snearma$with.Withtime,csaea,covaea,failcode=2,cencode=0) > > and in case b: >> covaeb <- >> cbind(sexb,fshb,fdrb,nsignb,eegb,th1b,th2b,stype1b,stype2b,stype3b,sty >> pe4b,stype5b,pgu1b,pgu2b,(ageb/10)^(-1),firstintb,log(totsezbaseb)) >> fitb <- crr(snearmb$with.Withtime,csaeb,covaeb,failcode=2,cencode=0) > > csaea and csaeb are the censoring indicators for a and b respectively which > equal 1 for the event of interest, 2 for the competing risks event and 0 > otherwise. > > Can anyone suggest a reason for the error message? I've tried running fitb > with variants of covaeb and irrespective of the order of the covariates in > the matrix, the code runs fine with 16 of the 17 covariates included but > then produces an error message when the 17th is added. > > Thank you for your help, > > Laura > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.