Stephen Foley: Google won't combine good and evil data

US Outlook: When Google announced its new policy on user data this week, the most important thing was not what changed, but what didn't.

The company is getting some heat from its decision to combine what it learns about the users who sign into its products. Now, the videos you watch on YouTube, the stuff you write in your Gmail messages, and what you type into Google Search will all feed the great Google algorithm, so it can spit out better search results and ads you are more likely to click on.

If you sign into Google, that is.

Frankly, I'm surprised it has taken Google so long to combine its users and their data already, and – given that the company has also come up with a comprehensible privacy policy – I don't have much truck with the jack-in-the-boxes who spring up on these occasions to attack the company.

Here is the important thing that didn't change: Google will not be combining what it learns through signed-in users of its products with the even more enormous trove of data it has on internet users through its DoubleClick advertising network.

DoubleClick's cookie tracks probably most of us around the internet, every time we browse a site that contains one of its ads. Perhaps you didn't know that. Too few people know that when you land on a website, it is not just that website that learns about your presence there, but also third parties that work with the website. You have to have done a lot of reading on this subject to know about these ad networks and how to stop them tracking you.

What you certainly do know is that Google's motto is Don't Be Evil. Google is sitting on two troves of data, "good data" that it gets from you when you knowingly sign in, and "evil data" that it collects behind your back. There's a good reason it isn't combining the two.