Chen-An Tsai earned his Ph.D. degree in statistics from the National Central University, Taiwan, in 1999. He started his professional career as a postdoctoral fellow at the National Center for Toxicological Research, FDA, USA. In 2005, Dr. Tsai was appointed to the position of associate research scientist at the Institute of Statistical Science, Academia Sinica. He is now a professor at the National Taiwan University and the director of the Master Program in Statistics. His research interests include bioinformatics, biostatistics, statistical machine learning, and the development of statistical approaches for medical data. The significance analysis of gene sets in expression profiles is his current contribution to microarray experiment studies.