similar to: confidence intervals for Harrell's c-index in survival setting

Dear R help My problem is very similar to the analysis detailed here. If we use the mayo dataset provided with the survivalROC package the estimate for Somer's Dxy is very negative -0.56. The Nagelkerke R2 is positive though 0.32. I know there is a difference between explained variation and predictive ability but I am surprised there is usch a difference given that even a non predictive model

Dear All, I am trying to calculate a 95% confidence interval for the difference in two c statistics (or equivalently D statistics). In Stata I gather that this can be done using the lincom command. Is there anything similar in R? As you can see below I have two datasets (that are actually two independent subsets of the same data) and the respective c statistics for the variables in both cases.

I have this maximum liklihood estimate problem i need to find the roots of the following: [sum (from i=1 to n) ] ((2(x[i]-parameter)/(1+(x[i]-parameter)^2))=0 given to me is the x vector which has length 100 how would I find the roots using R? I have 2 thoughts...... 1 is using a grid search ... eg. brute force, just choosing a whole bunch of different values for my parameter .... such as

Hi, I am using the validate function in the design library to get corrected Somer's Dxy for cox ph models. When my sample size is reduced from 300 to 150, the function complains (length of dimnames[1] not equal to array) and does not produce any results. There are no missing values in the data. Any suggestions for a work-around? Thank you in Advance. >

Hi everybody. I'm studying the Harrell's book on regression modeling strategies, and I'd like to replicate the examples using R (instead of S+). So how's going the porting of the hmisc and design libraries? Are there available, though in beta version? TIA, Stefano Calza -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read

2011 Regression Modeling Strategies Short Course by Frank E. Harrell, Jr., Ph.D., Professor and Chair, Department of Biostatistics, Vanderbilt University School of Medicine. 2011 Dates: Wednesday, March 9 (8:00AM-11:00AM), Thursday, March 10 (8:00AM-4:00PM) and Friday, March 11, 2011 (8:00AM-4:00PM). Location: Vanderbilt Campus; Sarratt Student Center (SARR) 216/220. Requirements: strong

Anyone from Chicago area interested in this course? Please email XLSolutions so they can schedule it in Chicago. We ran out of travel budget in my company :( Date: Wed, 2 Aug 2006 13:20:23 -0700From: elvis@xlsolutions-corp.comSubject: [S] Course***Dr Frank Harrell's Regression Modeling Strategies in R/Splus course *** September 2006 near you (San Francisco, Washington DC, Atlanta)To:

Hi R community, These days, I am writing some functions to work with 2-ways frequency tables ; you know all this tuff about measures of association: Chisq and derived (phi, cramer's v), tau b, tau c, somer's d and so on. So I consider all those functions could be gathered in a single R file, as they are coherent and dealing with the same problem / objective (analysis of crosstables).

I am having trouble getting a loop to work for the following problem. Any help would be much appreciated. Thanks. I need to find the slope and intercept from the linear regression of Drug Level on Day by Participant. There are a total of 37 Participants. I need to store the Participant, Label, Slope, and Intercept in a new data frame. This data is ordered by Participant number 37 total

Dear R-help, I am having a problem with the interpretation of result from validate.cph in the Design package. My purpose is to fit a cox model and validate the Somer's Dxy. I used the hypothetical data given in the help manual with modification to the cox model fit. My research problem is very similar to this example. This is the model without stratification: > library(Design) > f1

Dear R help, I am having a problem with the Design package and my problem is detailed here. I fit a cox model to my data and validate the Somer's Dxy using the Design package. (Because of computation time problem, i only try 10 bootstrap samples for the time being) This is the model without stratification: > library(Design) >

Dear list, I'm trying to concatenate the values of two columns but im not able to do it: i have a dataframe with the following two columns: X VAR1 VAR2 1 2 2 1 3 2 4 3 5 4 6 4 what i would like to

Does anyone have any ideas how I could do a power calculation for a log rank test. I would like to know what the suggested sample sizes would be to pick a difference when the control to active are in a ratio of 80% to 20%. Thanks Dan -- ************************************************************** Daniel Brewer, Ph.D. Institute of Cancer Research Email: daniel.brewer at icr.ac.uk

found by Christian T. Steigies <cts@debian.org> usr/include/arch/m68k/klibc/archstat.h:12: error: syntax error before '__dev64' better use __stdev64 defined in klibc/stathelp.h Signed-off-by: maximilian attems <maks@sternwelten.at> diff --git a/usr/include/arch/m68k/klibc/archstat.h b/usr/include/arch/m68k/klibc/archstat.h index 89c0341..dce25f9 100644 ---

Commit-ID: 3de648dd97d9d6086598aa80206a3007a13ed61b Gitweb: http://git.kernel.org/?p=libs/klibc/klibc.git;a=commit;h=3de648dd97d9d6086598aa80206a3007a13ed61b Author: H. Peter Anvin <hpa at zytor.com> AuthorDate: Mon, 11 Nov 2013 19:41:55 -0800 Committer: H. Peter Anvin <hpa at zytor.com> CommitDate: Mon, 11 Nov 2013 19:46:47 -0800 [klibc] arm64: Fix struct stat Use actual

Hi All, a colleague wants to calculate the Fisher information matrix for a model he wrote (not in R). He can easily get the neg-log-likelihood and the best fit parameters at the minimum. He can also get negLLs for other parameter values too. Given these data, is there a way in R to calculate the Fisher information matrix? Best, Federico -- Federico C. F. Calboli Department of Epidemiology

Simple question how can you position text in the top left hand corner of a plot? I am plotting multiple plots using par(mfrow=c(2,3)) and all I want to do is label these plots a), b), c) etc. I have been fiddling around with both text and mtext but without much luck. text is fine but each plot has a different scale on the axis and so this makes it problematic. What is the best way to do this?

Dear All, I saved by mistake the environment I was working in after typing q(), and now I get the annoying message: [Previously saved workspace restored] I have already deleted all the objects in the environment, saving it as an empty environment, so it's just a matter of nitpicking I suppose. The message does not appear if I start R from any other place in the directory tree. I am

Hi All, I have a list of matrices: > x [,1] [,2] [1,] 1 4 [2,] 2 5 [3,] 3 6 > y [,1] [,2] [,3] [,4] [,5] [,6] [1,] 18 21 24 27 30 33 [2,] 19 22 25 28 31 34 [3,] 20 23 26 29 32 35 > z =list(x,y) I want to create a second list that is has a subset each matrix in the list subsetting so I get the 2nd and 3rd row of each (and

Hello, I would like to reshape my data for presentation purposes from something like this: > test <- data.frame(a=c("A","A","A","A","B","B","B"),b=c(1,1,2,2,1,1,1),c=1:7) > test a b c 1 A 1 1 2 A 1 2 3 A 2 3 4 A 2 4 5 B 1 5 6 B 1 6 7 B 1 7 to something like this: a b c 1 A 1 1,2 3 A 2 3,4 5 B 1 5,6,7 This seems