App Store rankings rejiggered in move to iOS 6

Maps weren't the only thing to get a tweakwith iOS 6. Apple appears to have changed how it determines the rankings on its App Store as well.

In a new post today (registration required), BTIG Research notes what it calls "dramatic" differences in the list of Top 25 free apps on Apple's App Store between yesterday and today, a period of time that also brought the release of iOS 6.

iOS 6 comes with complete redesigns of all Apple's digital stores, from iTunes to the iBookstore to the App Store. But there might have been some significant changes under the hood as well, BTIG Research's Richard Greenfield writes.

"While the iOS app store ranking methodology has never been fully disclosed by Apple, we believe it has been heavily influenced by the velocity of downloads, not overall popularity/installed base," Greenfield says.

As a result, some apps that were in the top fell off almost instantly, while others that were previously not in the Top 300 knocked off longtime placeholders. That includes apps from Zynga, Facebook, and Pinterest, all of which fell off the list.

Why is this kind of placement so important, you might be wondering?

"For app developers, being in the Top 25 and especially in the Top 10 has been critical, as consumers often check for new Top 10/25 apps on their iPhones regularly, not bothering to scroll through multiple screens to see Top 50 or Top 100 apps," Greenfield says.

Applications that break into the Top 25 lists can get a dramatic number of downloads and purchases, an effect that can snowball and push some higher and higher. The process can also be beneficial to developers who produce "lite" and iPad versions of their applications, where visibility can push the application's paid counterpart to the top as well.

CNET has reached out to Apple for more information. We'll update this post when we know more.