Replication is the cornerstone of science. Its absence reduces any scientific endeavor to a set of unverified beliefs. Brain imaging studies are no exception, though they have several specific characteristics that conspire to make quantification of reliability especially difficult. First, measurements are complex and idiosyncratic for each modality. Secondly, the definition of the actual target to be measured is often imperfect. Thirdly, the data sets are very large and not amenable to standard investigations of replication.
