Hi all, i was wondering if anyone could help mw. I am trying to calculate the correlation between two replicates spots. I triied following the manual and the bioC website but have not managed to understand why it is not working for me. I got this message : > cor <- duplicateCorrelation(RG, design, ndups=2, spacing=5376) Error in dim(M) <- c(spacing, ndups, ngroups, nslides) : dim<- : dims [product 86016] do not match the length of object [87552] thank you to help. Regards, Benoit Houeix Gene regulation group National diagnostics centre, NUIG Galway, Ireland. 00353 91492077.