From: WOLFGANG LUDWIG-MAYERHOFER To: fharrell@virginia.edu Subject: Review of Survival Analysis Software Date: Tuesday, January 13, 1998 5:28 AM Dear Prof Harrell, I have read your fine review of statistical software for survival analysis in the "American Statistician". I was surprised, however, to see that the TDA (i.e. Transition Data Analysis) program was not included, which is one of the most powerful packages for doing such analysis (for instances, including time-dependent covariates for all models through splitting of episodes -- for which the program also supplies a powerful subpackage). TDA certainly is not very userfriendly, and it does not offer the flexibility of S-plus, but on the other hand it offers a wide range of additional procedures, including the output of excellent graphics for postscript printers. TDA is well-known among applied researchers, such as sociologists or economists, but you may have had reasons for not including it in your review. However, in that case I would liked you to have stated these reasons in your paper. In addition, the program has the advantage that it is available at no cost. I do hope that this is not the reason that you did not include it. Much of the survival analysis part of the program is described in a book by Hans-Peter Blossfeld and Goetz Rohwer (the program author): Techniques of Event History Modeling, Mahwah, NJ: Erlbaum Publ., 1995. You can find information about the program, and also download it, from: http://www-soep.diw-berlin.de/~jpd1/tda/tda.htm Yours sincerely Wolfgang Ludwig-Mayerhofer IMPORTANT: SEND REPLY TO THE FOLLOWING ADDRESS ONLY! Email: WLM@lrz.uni-muenchen.de Mail, Phone, Fax: Institut fuer Soziologie der LMU Muenchen Konradstr. 6 D - 80801 Muenchen Tel. ++49 - (0)89 - 2180 3223 Germany Fax. ++49 - (0)89 - 2180 2922 Internet: http://www.lrz-muenchen.de/~ls_allmen/wlm.htm (German) http://www.lrz-muenchen.de/~ls_allmen/e_wlm.htm (English)