Thanks everybody for dispersing my ignorance of multilevel analyses. I was stunned by the amount of information. For the benefit of others I enclose the links that were sent to me.

http://www.ioe.ac.uk/mlwin/ <http://www.ioe.ac.uk/mlwin/>

http://www.fss.uu.nl/ms/jh/ <http://www.fss.uu.nl/ms/jh/>

http://www.ssicentral.com <http://www.ssicentral.com>

best

Staffan Lindberg National Institute of Public Health Sweden