Enter and die at the same time

Stata does not allow a subject enters the risk set and dies at the same time, here is an explanation:

http://www.stata.com/support/faqs/stat/zerohelp.html

Human interface device

Sometimes not all tray icons show up (after a new boot). This can be caused by a unexpected stop in the human interface device. Re-start that service and reboot the computer should solve the problem.

Some R related materials

I have been leaning toward R gradually. Here are some useful resources in learning and using R:

http://faculty.chicagogsb.edu/peter.rossi/research/bayes%20book/bayesm/Making%20R%20Packages%20Under%20Windows.pdf

http://www.maths.bris.ac.uk/~maman/computerstuff/Rhelp/Rpackages.html

http://www.bioconductor.org/workshops/2006/biocintro_oct/lectures/R_intro.pdf

A good GUI for R is JGR: http://rosuda.org/JGR/