These guys have been contributing to JDT by reporting a bunch of bugs based on their findings, so I thought I should talk about them :)
The aim of CodingSpectator project is to study how developers interact with the Eclipse IDE, by collecting and analyzing usage data. CodingSpectator has been developed at Ralph Johnson’s research group by the following graduate students: Mohsen Vakilian, Nicholas Chen, Stas Negara, Roshanak Zilouchian and Balaji Ambresh. Ralph is a co-author of the seminal book on design patterns (GoF) and his research group has a history of important contributions to IDEs. CodingSpectator monitors programming interactions non-intrusively in the background and periodically uploads it to a secure server at UIUC.
They have presented some of their findings in this technical report - Use, Disuse, and Misuse of Automated Refactorings. Based on the same report they have reported a number of insightful bugs against JDT and also provided suggestions on how some of the refactorings can be improved. A few bugs have already been fixed. In addition their technical report also improved my understanding of an average JDT user's behavior. Thanks guys!
Probably the biggest challenge with a usage study is finding a good number of participants. They are looking for more participants in order to continue their research study. If you’re interested in helping the researchers out, you could install CodingSpectator.