Denis, in a sense you were right not to post in english because it seems that you are facing a very serious fortune(122) problem. Some R practicals in french are available here: http://pbil.univ-lyon1.fr/R/enseignement.html Good luck -- Jean R. Lobry (lobry at biomserv.univ-lyon1.fr) Laboratoire BBE-CNRS-UMR-5558, Univ. C. Bernard - LYON I, 43 Bd 11/11/1918, F-69622 VILLEURBANNE CEDEX, FRANCE allo : +33 472 43 12 87 fax : +33 472 43 13 88 http://pbil.univ-lyon1.fr/members/lobry/