The life-blood of comparative empirical research on how law departments function has to be survey data, since no one aside from a handful of consultants develops any multi-department understanding. We rely on responses by law department lawyers, even though a well-documented flaw in many surveys may contest the accuracy of the data.
The flaw is that many survey respondents dislike saying that they have no knowledge or no basis for an answer; they blush not to give an uninformed opinion (See my posts of May 17, 2006 where many respondents assessed judicial districts even though they had no first-hand experience; of Aug. 28, 2006 on probably subject opinions as to whether law firms make too much money; and May 24, 2006 on the dreamed up payoffs from alternative billing arrangements.).
We often have nothing better to draw on than survey responses, but we should not blind ourselves to the risk that some respondents gave answers even thought they didn’t have a clue.