Turn, a Redwood City, Calif. ad network that recently took 15th place in a ComScore survey of the top networks by reach, has raised a $15 million third round of funding.

The company is one of several that put the focus on the return on investment for advertisers, regardless of the site their ad is placed on. So, for instance, if Turn’s data tells it that an ad would be better placed on a small blog than a large news site, that’s where the ad will go.

How that determination is made relies on a number of factors, but both the content on sites and the average profile of their visitors play in, to create multiple data points that both tell Turn what to charge and where to place ads. In March, when we covered the company in more depth, it had some 500 advertisers and over 3,000 websites participating.

Turn’s style of targeting is getting plenty of attention lately, with only two days having passed since Lotame picked up a $13 million funding. The main difference between the two is that Lotame places more emphasis on visitors with its “Crowd Control” technology, which seeks to tap into audiences that have proven they’re interested in a subject, often on social media sites.

The $15 million financing to Turn was led by Focus Ventures. Previous investors Norwest Venture Partners, Trident Capital and Shasta Ventures also came in for the round. Turn’s previous round was also for $15 million, leaving the company with around $35 million to date.