Quoting Counterpane
More excellent quotes from Bruce Schneier's Crypto-gram for 15 Jan 2004.
From Diverting Aircraft and National Intelligence
More raw data can even be counterproductive. With more data, you have the same number of "needles" and a much larger "haystack" to find them in. In the 1980s and before, East German police collected an enormous amount of data on 4 million East Germans, roughly a quarter of their population. Yet even they did not foresee the peaceful overthrow of the Communist government; they invested too heavily in data collection while neglecting data interpretation. (emphasis mine)
Hell of a thing to miss.
Terrorists and Almanacs is also good reading. We have actual government law enforcement officers who think carrying an almanac is dangerous. A referenced weblog entry (Consider the source) just led me to a kindred spirit.