We didn’t really believe it when we were told in 7th grade that math could unlock the secrets of the universe, but after reading about the coupon-wielding power of a Target statistician, which resulted in a mighty surprise for one father of a teenage girl, we might be converts. Doesn’t make math any better though.

The New York Times (via Forbes) had some time chatting with Target’s statistician royale, Andrew, before he was told to zip his lips by the company. He discussed how retailers figure out how to sort out your purchases — from what you need, what you will use a coupon for and your personal preferences. Oh yeah, and they can decode if you’re pregnant even before you buy diapers.

In Target’s case, it all comes down to your Guest ID number tied your credit card, name, and other info, which saves all kinds of data about what you buy. Statistician Andrew mined that data and saw patterns in it, for example — women on baby registries buy larger amounts of unscented lotion around the beginning of their second trimester. Bam! Send’em some coupons for other baby items. More Andrew magic!:

As [his] computers crawled through the data, he was able to identify about 25 products that, when analyzed together, allowed him to assign each shopper a “pregnancy prediction” score. More important, he could also estimate her due date to within a small window, so Target could send coupons timed to very specific stages of her pregnancy.

Freaky! Those scores lead Target to send coupons for baby items to their customers with certain pregnancy scores. One unsuspecting and angry father even stormed into a Target to yell at them for sending his daughter coupons for baby clothes and cribs. Turns out, she was pregnant, and hadn’t told her father yet. Awkward. He apologized to Target.

Soon enough, Target learned they shouldn’t creep people out by knowing too much about them, so they switched up their coupon booklets. That means an ad of a lawn mower next to a crib, or a set of plates alongside baby clothes. Sneak attack, and no one can yell at you for being pregnant.

*Thanks to Beth for the link!

How Companies Learn Your Secrets [Chicago Tribune]