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Related How Companies Learn Your Secrets New York Times

In Charles Duhigg’s new piece for the New York Times, a father finds himself in the uncomfortable position of having to apologize to a Target employee. Earlier he had stormed into a store near Minneapolis and complained to the manager that his daughter was receiving coupons for cribs and baby clothes in the mail.

Turns out Target knew his daughter better than he did. She really was pregnant.

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It was a fact Target had obtained after carefully collecting information about her. The company, like many others, assigns each shopper a unique Guest ID. Every time you buy toilet paper with a credit card, visit its website, fill out a survey or, really, interact with the retailer in any way, Target assigns this information to that ID.

Major disruptions in your life—weddings, job changes and especially babies—are gold mines to retailers, who finally have a chance to break into your well-worn routines. That’s why Target hires statisticians like Andrew Pole to sift through data to try and identify when someone is approaching or undergoing one of these major life events.

Here’s how Target knew the young woman was pregnant:

As Pole’s 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.

For all of the constant noise generated by the press, most people don’t really care about their privacy. Don’t get me wrong; they care about the principle of privacy. It certainly feels icky to know that companies are tracking your every move.

They don’t, however, care about the act of being tracked, or not enough to change their behavior in any significant way. The thought of their data floating around in a market that they’ll never see is just too abstract.

Then something like this happens. It’s not hard to see the implications. Getting divorced? Sign up for our dating website! Just lost a loved one? Buy these flowers!

So how do you stop companies from knowing everything about you? The short answer is that unless you start living like a survivalist, it’s extremely difficult to completely stay off of corporate America’s radar.

A study in October at Carnegie Mellon University found that tools meant to limit online behavioral advertising (OBA) were either ineffective or too confusing for most people to use. That included browser tools, third-party blocking tools and opt-out tools from several advertising networks:

Our results suggest that the current approach for advertising industry self-regulation through opt-out mechanisms is fundamentally ﬂawed. There are signiﬁcant challenges in providing easy-to-use tools that give users meaningful control without interfering with their use of the web. Even with additional education and better user interfaces, it is not clear whether users are capable of making meaningful choices about trackers.

That doesn’t mean you can’t spend some time trying to figure out a program like TACO. Even if the interface is confusing, it’s still better than nothing.

Another good idea is to safeguard your information by only going to websites that respect your privacy. A new site built by PrivacyChoice does just that.

Enter a URL into privacyscore.com and it will rate it from zero to 100 based on the number of trackers on every page. The three worst offenders so far, according to the site: merriam-webster.com, tvguide.com and nypost.com. Target.com, by the way, has a mediocre privacy score of 48.

Avoiding email lists and surveys are also a good idea, not to mention carrying around a lot of cash. Or you could just accept the inevitable—most people are willing to sacrifice a lot of privacy for convenience. Unless consumers revolt or the government acts, in the future shoppers won’t have the option of opting out.

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