The error was the result of bad math.
The National Security Agency assured Americans last week that it only surveils a tiny percentage of the Web data it collects. But it turns out the NSA screwed up the math, and that percentage was off by an order of magnitude.
That error is in a document released by the agency on the heels of the president's speech earlier this month announcing measures to review NSA surveillance. We described the math at stake last week, but the pertinent section is this:
Unfortunately, if you do the math in suggested by that paragraph, you don't get that tiny percentage, 0.00004 percent, or 4 parts per 10 million. It's actually 0.0004 percent , with one fewer zero — or 10 times as much as the NSA suggested. It's ten dimes on the basketball court, not one.