Dear Jens, "2008" is a good year for epidemiology and statistic... Thank you for your work and the new versions of EPIDATA Analysis 2.xx. The "lifetable" programs are very interesting for epidemiologists. I hope that 2009 year will a new good year for you and for us, happy users of this software.
For your interest, I join a file with four variables and 239 lines. "Arret" is outcome variable (1=interest), and "durall" time variable in weeks. Plus two variables "plaisir" and "moment" in two categories (1 and 2). The result of lifetable command with "lifetable arret durall /by=plaisir /p50 /t" is curious (with version 159 and anterior) instead of "7" or "8" for the categorie "plaisir=2" (probability of 0.50). It's OK with variable "moment". Why the reason ?
Sincerely
Bernard Branger
PS : The link for "Course materials in French" is the following : http://www.reseaunaissance.com/joomla/index.php?option=com_content&task... egory§ionid=20&id=70&Itemid=148
Bernard,
I think that the problem is a bug in the estimation of median survival proportions when there are no survivors in one group (for plaisir=3, all 8 records have arret=1). If you invert plaisir, by the way, (recode 1 to 2, 3 to 1), it may work, but not consistently. If you want the p50, then you can run the analysis for level 3 of plaisir alone:
lifetable arret durall /p50 if plaisir=3
This seems to work all the time.
Jamie
Bernard wrote:
For your interest, I join a file with four variables and 239 lines. "Arret" is outcome variable (1=interest), and "durall" time variable in weeks. Plus two variables "plaisir" and "moment" in two categories (1 and 2). The result of lifetable command with "lifetable arret durall /by=plaisir /p50 /t" is curious (with version 159 and anterior) instead of "7" or "8" for the categorie "plaisir=2" (probability of 0.50). It's OK with variable "moment"
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