[R] Paired -test in NADA package

Hi all, I would like to run a paired t-test with censored data using the NADA package. Here is an example data set: data <- data.frame(group=rep(c('a','b'), each=6), obs=c(2,2,5,7,10,10,5,5,6,8,5,9), cen=c(T,T,F,F,F,F,F,F,F,F,F,F)) #A two sample t-test can be executed as follows: library(NADA

[R] Which date format to choose?

R offers a bewildering array of options when it comes to representing dates and times (e.g, as.Date, chron, strptime, zoo, etc). Can anybody recommend a document that compares the relative merit of each method? I'm not looking for help with any one method, but rather a guide that describes wh