To give credit where credit is due, if it were not for self-interest much of the research reported in these posts would not exist. Advocacy groups and vendors abound, and some of them survey law departments in support of their positions or offerings. My flashing yellow light has to do with objectivity: we must all be cautious regarding data that might be skewed by the views of the group that gathers and analyses it.
Without impugning the quality of any of the facts found by these gatherers, here are some of the purposive survey results I have encountered. See my posts regarding proponents of alternative dispute resolution (ADR) (Dec. 9, 2005), executive search firms (March 12, 2006 and diversity among general counsel), technology vendors (May 1, 2005 and electronic billing), legal research (Jan. 16, 2006 about savings), consultants (Oct. 29, 2005), trade groups (June 6, 2006 and the Federal Judicial Center), expert witnesses (May 17, 2006), electronic billing vendors (Jan. 4, 2006), and law firms (April 7, 2006).
In other words, every cottage in the legal village produces what may be self-serving data, which does not mean the data is inaccurate, but which does mean that those who act on the data ought to bear in mind the source.