Hi all I'm running gcRMA via affylmGUI on data from the ATH1 chip The expression levels I get now are very slightly different to those I got at the end of last year. I'm assuming something has been updated, but does anyone know what exactly? Is it the implementation of gcRMA, or is it more likely to be changes in where we think the probes map to? Thanks This message has been checked for viruses but the contents of an attachment may still contain software viruses, which could damage your computer system: you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation.