Inside Mobile Apps reports that Apple has made changes to its App Store ranking algorithm, to add additional criteria alongside the number of downloads made. Apparently, mobile apps analytics firm Flurry noted changes over a number of days, stating that “Apple is absolutely considering more than just downloads, which we believe is the right direction to go in to measure the true popularity of an app.” It was suggested that the company now includes an assessment of usage in its calculation. This enabled, for example, Facebook to climb to the number one position despite having been ranked lower than number 10 for some time. Apple has not commented on the changes.

It was subsequently suggested that Apple has changed the weightings given to certain product categories, so that (for example) social networking app downloads count for more than games. While this affects the top apps listing, titles should maintain the same positions within their categories. This change would make it easier for titles in less popular categories to gain visibility, but at the expense of the biggest titles in the most popular groups.

Earlier this month, it was reported that Google has also begun taking usage into account in its Android Market rankings, again with the effect of shaking-up its listing of top titles. As with Apple, it has not commented on the changes.

It was noted that the change in app store ranking model comes at a time when many developers had begun tweaking their business models in order to get the best results from this model. For example, a number have moved away from offering paid downloads to support in-app billing, in order to grow their customer base through free downloads – and thereby increase their position in the charts before monetising the installed customer base using the app.

In addition, several networks have grown up to enable developers to pay to have their app promoted to users, in order to increase visibility and generate more downloads – an option that may become less attractive if use is also now an key consideration. Separately, PocketGamer reports that Apple has begun removing apps from the App Store which use “incentivisation schemes” to attract users, for example by offering in-game credit for apps they are using in return for downloading another product. It was noted that “the vast majority of the freemium industry use it, but, for example, in Glu Mobile’s Big Time Gangsta, you can earn 7 Creds for downloading Pocket Gems’ free Tap Zoo or 61 Creds for GameDuell’s US$4.99 Cleopatra’s Pyramid. Within Big Time Gangsta, 65 Creds would otherwise cost US$9.99.”