This database was built by collecting publicly available microarray data profiled on Affymetrix U133A chips. Raw CEL files were obtained and normalized as a single experiment. The resulting data was filtered and processed for enrichment in specific tissues.
What is an enrichment score? On such large panels, every gene is differentially expressed. To identify genes that are tissue specific an enrichment scores is used to benchmark expression levels in one tissue compared to all other tissues. Genes that are widely expressed score low and around 0. However, genes that are specific score closer to 1. The enrichment score allows comparison between genes and therefore can be used to rank genes in each tissue.
