Apple has made changes to the way it ranks its top mobile applications in its iTunes App Store. The new rankings appear to take in consideration additional data points beyond raw download numbers, it appears. The changes should lead to more accurate lists of the top free and paid apps across the app store because, as every good developer knows, installs alone don't paint the best picture of an app's true popularity.

So what exactly has Apple changed to improve the app rankings and why?

According to a report from Inside Mobile Apps, Peter Farago, VP of marketing at analytics firm Flurry, noticed the change last week, but says it's too early to hypothesize what those changes may involve. The article speculates that Apple may be considering other factors like active usage and ratings, however.

Fighting App Store Shenanigans?

One person we spoke to about the change wondered if the move was perhaps prompted by recent reports of gaming behaviors in the app promo ecosystem, such as those documented here by Chris Dixon, the co-founder of Hunch. In early April, he noticed that many of the top rated and top ranked apps were actually, "pretty scammy," he said.

In one example, he downloaded a highly ranked Utility called "Night Vision," only to find the app didn't even work. The app was also rated highly when viewed in the mobile iPhone App Store, but was rated poorly on the desktop App Store. This is because the developer knew that by submitting "new versions" of the app, they could reset the ratings in the mobile store.

Dixon wasn't the only one to notice such issues. Bijan Sabet, a partner at Spark Capital, also revealed that the startups in Spark Capital's portfolio are often pitched by third-parties offering app store optimizations, including cross-promotions, pay-for-distribution plays and even tricks that take advantage of the app store's rules itself to provide better rankings.

It's possible that these rankings changes by Apple is a direct response to some of these ploys.

Highlighting Editorially Selected Apps?

Another theory being circulated by those in the industry is that the revised rankings are still primarily install-driven, but Apple has begun to factor in other things as well. One such factor is category rank - meaning, an app that makes it to the top of its category may have a better chance of ranking highly in the overall rankings. This source, who has chosen to stay anonymous, also says there may be even more to it than that.

It sounds like Apple has set aside certain slots in their top rankings for other cool apps it wants to highlight, they said, regardless of how many installs it has.

That, of course, would be a dramatic change on Apple's part, but for now, this is just a theory.

Rejecting Incentivized Installs

In addition, a new report from today states that Apple isn't just tweaking rankings, but has actually gone so far as to ban apps that use pay-per-install methods, according to GigaOm. The report references a statement from app marketing firm Tapjoy, which claims that Apple is now banning what it describes as "the largest and most effective channel for app installs." The effect, says the company, will have "a long-term negative impact on the user experience, developer innovation and advertiser utility."

A second report from PocketGamer also found this to be the case, noting that several apps were rejected upon submitting updates because they used virtual currency in exchange for app downloads.

These changes will have a major impact on the app ecosystem, and will have the most effect on smaller app development shops looking to gain exposure through the use of marketing techniques like these. Clearly though, Apple does not want its rankings and ratings to be gamed in any way, and has adjusted its system accordingly.

We asked Apple to comment on these changes, but of course, have not heard back.

If you're a developer, how have these changes affected you? Let us know what you think about all this.