Hello everyone, I'm new to this mailing list, so please forgive my simple question. I'm trying to use the tissue specific genome wide expression data from table affyExonTissues in UCSC. I see in the description that
> *RNA (from a commercial source) from 11 tissues were hybridized to > Affymetrix Human Exon 1.0 ST arrays. For each tissue, 3 replicate > experiments were performed for a total of 33 arrays. The raw intensity > signal from the arrays was normalized with a quantile normalization method, > then run through the PLIER algorithm. The normalized data were then > converted to median-centered log-ratios, which are displayed as green for > negative log-ratios (below-median expression), and red for positive > (above-median expression).* > What I cannot understand is how to obtain a unique representative expression value for each tissue, to be compared to the values in other tissues, if possible. I understand that in the columns *expIds* and *expScores* contain the 33 experiments ids and results for the 11 tissues. But which experiment is for which tissue? And why are some expression values negative? And why do many probes have the same *bin* value? And what does the *score *column stand for? Thank you very much in advance Emanuele Osimo Dept of Science & Biomedical Technologies - Fondazione Filarete and School of Medicine, University of Milan, Milan, Italy _______________________________________________ Genome maillist - [email protected] https://lists.soe.ucsc.edu/mailman/listinfo/genome
