search for: rappold

Dear all, I have two probably very easy questions: (1) Is there a way to access certain variables by their string-based name representation? Example: numbers <- c("one", "two", "three") varname <- "numbers" print(varname[2]) (2) I need this functionality for a customized na.exclude() function that I am building, which should only exclude rows

Sorry guys, but I have another one: I want to write a function that returns a certain column of a dataframe. The function accepts two argument: the dataframe and the name of the column, but the column is not given as a "string" but as a variable name. EXAMPLE ---------------------- > testdata start stop censor groupvar var1 var2 1 0 1 0 1

Dear all, does anyone know how I can extract specific p-values for covariates from an aftreg object? After fitting a model with aftreg I can find all different variables by using str(), but there's no place where p-values are kept. The odd thing is that print() displays them correctly. EXAMPLE: > testdata start stop censor groupvar var1 var2 1 0 1 0

Dear all, I have some trouble using the "id"-argument with aftreg (accelerated failure time regression analysis from the eha library). As far as I understand it, the id argument is used to group individuals together if there are time-varying covariates and the data is arranged in counting process style. Unfortunately, i cannot figure out how to use the "id"-argument. The

Dear Prof. Brostr?m, Dear R-mailinglist, first of all thanks a lot for your great effort to incorporate time-varying covariates into aftreg. It works like a charm so far and I'll update you with detailled benchmarks as soon as I have them. I have one more questions regarding Accelerated Failure Time models (with aftreg): You mention that left truncation in combination with time-varying

Dear friends, I have used R for some time now and have a tricky question about the coxph-function: To sum it up, I am not sure whether I can use coxph in conjunction with missing covariate data in a model with time-variant covariates. The point is: I know how "old" every piece that I oberserve is, but do not have fully historical information about the corresponding covariates. Maybe you

Dear all, does anyone know if it is possible to connect a Windows RExcel instance to a linux R instance? Within Rexcel, I find the option "Remote Server Address", but I wonder what the installation procedure on my linux (ubuntu) R looks like (if possible at all)? Thanks Philipp

I have one more conceptual question though, it would be fantastic if someone could graciously help out: I am using an accelerated failure time model with time-varying covariates because I assume that my independent variables have a different impact on the chance for a failure at different points in lifetime. For example: High temperature has a different impact on failure in earlier years

G?ran, thanks for the update, I'm just about to install it! Just wanted to drop you a short line about performance (as you once requested): aftreg takes ages on my windows machine to calculate a small set of 7 observations which are not even grouped together by "id". To be a bit more precise, it takes 2:40 mins on my Intel T9300 Core2 Duo @ 2.5 GHz. Bigger samples with about 700

Dear R-community, Dear Prof. Therneau, I would like to fit an AFT-model with time-dependent covariates and right-censored data. Searching the mailing list for information on the subject, I found some old posts which said it didn't work back then. My questions: (1) Has this kind of fitting already been implemented in the survival library in R? (2) If not: Are there any alternatives/