search for: umberto_maggior

I cannot figure out how, using R, I can paste indexes or characters to the variable names which are used within loops. I will explain this with a simple example: Immagine I have a huge series of variables, each one taken two times, say x1 x2 y1 y2 z1 z2..... Now, immagine that I want to compute a variable from the difference of each couple, say dx=x1-x2, dy=y1-y2, dz=z1-z2... In Stata, for

using either one of the following codes: xyplot(X ~ time | center, type="l", panel=panel.superpose, groups=subject, col = treatment) xyplot(X ~ time | center, groups = subject, panel = function(x, y, ...){ panel.superpose(x, y, col = treatment, type = "l", ...) }) I get two different colours for the lines by these colours do not match the corresponding treatment

I am a new user of R for Windows, enthusiast about the many functions of the Design and Hmisc libraries. I combined the results of a Cox regression model after multiple imputation (of missing values in some covariates). Now I got my vector of coefficients (and of standard errors). My question is: How could I use directly that vector to run programs such as 'nomogram', 'calibrate',

Using data from a multicenter study with a parallel-group design comparing two treatments, I plotted each subject's time change of X after stratifying for center: xyplot(X ~ time | center, type="l", panel=panel.superpose, groups=subject) Now I want these lines to take different colours according to the variable "treatment". Any help? Umberto