Comparison of meta-analysis to combined analysis of a replicated mi- croarray study

The widespread use of microarrays has resulted in a large-scale, rapid expansion of data. Many research groups throughout the world are engaged in gene expression studies of the same or similar conditions – specific cancers, for example. Data from many microarray studies are deposited in publicly available databases such as Gene Expression Omnibus (GEO; Edgar et al., 2002; Barrett et al., 2005). It is hoped that ready access to primary data will facilitate the integration of information across studies.