A great article by David Gerwitz with some much-needed perspective on what the numbers really tell us about NSA surveillance: Data-Driven Analysis Debunks Claims That NSA Is Out of Control (Special Report).

Let’s start with a basic problem. Big numbers are hard for people to visualize. Really, really, really big numbers are impossible to visualize.

The gotcha that comes out of this cognitive limitation is that it’s possible to distort public perception by tossing out big-sounding numbers. Even if an attempt is made to put those numbers in perspective, most readers grab the most savory bit of information, usually from the headline, and that’s what becomes their internal representation of the facts.

So let me summarize the results of my data-driven investigation, and then take you through the details. Here is a summary of the results of my analysis:

• Facebook captures 20 times more data per day (for just its server logs, not counting everyone’s posts) than the NSA captures in total.
• The NSA’s selection systems are actually insanely accurate. If you compared all the data they capture to a year’s worth of time, the amount of errors they make amounts to about a quarter of a millisecond.
• The actual byte quantity of erroneous data the NSA records amounts to less than one MP3 track per week.
• If these numbers were reported in a corporate situation, they would be considered an absolute triumph of big data management and implementation.

So, there you go. Headlines hyper-inflate the facts. Now let me take you through all the details.

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