Hi All First of all, thanks for helping with normalize.quantiles function. I am trying to normalize intensity data from 4 different CEL files using normalize.quantiles function. However I understand that this function needs a matrix of data. I need to somehow try to map the intensity data from 4 CEL files to the same probe position and put it in a new file before normalizing. I was looking into BufferedMatrix.read.celfiles function. I have two questions: 1. I did load the BufferedMatrix package and the Affy package, however the R program is nor recognizing the function. 2. Is there any other way to achieve data normalization from different data sources. Please note that I was unable to find CDF file for the tiling array we used(GeneChip Human Tiling 2.0R array set). So I am thinking using rma may not work without CDF file. Thanks. - Radhika [[alternative HTML version deleted]]