i had this problem many years ago (15?).  at the time i was working as a postdoc, calculating the evolution of the ionizing background with redhshift from the inverse effect (lyman alpha clouds near quasars get fried by the quasar; the extent of this gives an indirect way to measure the ionizing background at that redshift).<p>i had a bunch of perl scripts (ah, those were the days) that mangled various files before feeding them into fortran least-squares stats code that took a day or so to run.<p>by the end, it was pretty much chaos.  i was a self-taught programmer, these were probably the second or third "significant" programs i had ever written.  nothing was documented, everything took so long that i couldn't check much...  i had bugs, of course.<p>in the end i published.  maybe 6 months later i got an email from someone in the states.  they were trying to reproduce my results.  in the end, they did (as far as i know).<p>so the system worked.<p>incidentally (perhaps the only useful point here) they must have used different data.  that's something worth explaining in more detail - "my" data came from years of painstaking work by a bunch of people working for my thesis supervisor.  yet 6 months later the results could be duplicated from a week or so of data from a much more powerful telescope (the keck).  so data in research often aren't as critical as you might think.  things progress at such a rate that even if you don't share data, it's trivial to reproduce just a short time later... (and i am pretty sure that this is true in gene sequencing, for example)