Wired has a short article on how a software bug might have helped Deep Blue defeat Gary Kasparov in their famous match in 1997. The bug caused the computer program to choose a play at random; the play wasn't devastating in itself, but Kasparov was so flustered by how counter-intuitive it was that he was thrown off his game. Kasparov assumed that the move had an intellect behind it, and since the move didn't appear to make sense he assumed that the machine was looking very deeply into the game and seeing something sublime. He assigned a meaning to randomness and was dismayed at what that implied.
This is something we humans do all the time, and we're only occasionally aware of it. We see something in the world and construct a story that makes sense of that thing. We weave a narrative that includes character and motivation; only sometimes are we in the position of knowing whether our story actually makes sense.
Consider web analytics. You have pages and articles, clicks and time spent on page. From numbers your goal is to derive meaning: customer intent that is either frustrated or fulfilled by your site design. You isolate a feature -- your home page bounce rate, for instance -- and tell a story: we're disappointing our customers. You're never going to meet more than a handful of those site visitors, though, so the story you tell exists entirely in the realm of the hypothetical.
You do what you can to make things less hypothetical, of course. You aggregate numbers, for instance, and resist the urge to find too much meaning in smaller collections of clicks. But another feature of human intellect is we notice irregularity. The familiar, day-to-day rhythms of your life and your website soon cease to capture your intention. Instead, your eye is drawn to what's new and different, the things that you didn't expect. Like Kasparov, you obsess about what you can't understand. And, like Kasparov, you probably don't take the time to think that something that's inexplicable might simply lack a rational explanation.
There is noise in your signal. Practice the art of hearing the noise and not mistaking it for a hidden, more meaningful signal.