Hi Rachel It is the residuals which need to be independent and identically (normal) distributed, not the covariates of interst. Hope this helps Torben Torben Ellegaard Lund Assistant Professor, PhD The Danish National Research Foundation's Center for Functionally Integrative Neuroscience (CFIN) Aarhus University Aarhus University Hospital Building 30 Noerrebrogade 8000 Aarhus C Denmark Phone: +4589494380 Fax: +4589494400 http://www.cfin.au.dk [log in to unmask] Den 20/04/2008 kl. 05.32 skrev Rachel Grossman: > Hi SPM community, > > > I have a question concerning the distribution of covariates of > interest. How does SPM deal with covariates of interest that are not > normally distributed? For instance if the values are skewed toward > the minimum and the maximum limits? > > > Thanks for your advice, > > Rachel > > > Be a better friend, newshound, and know-it-all with Yahoo! Mobile. > Try it now.