Google saw an increase of 600 per cent in app revenue in 2012, doubling from quarter three to quarter four alone, but Apple's iOS App Store still generates more than three times as much as Google Play, according to new research.

Research group App Annie has found that customers buying games in Japan and South Korea, plus growing sales of Android smartphones, have contributed to Google Play's rapid gain in popularity, reports Bloomberg.

While Google Play may have made the company six times as much in 2012 as it did in 2011, Apple's App Store still generated about 3.5 times more revenue in December than Google's store, App Annie reports.

"Both platforms are very healthy," said App Annie's vice president of marketing Oliver Lo. "More and more publishers are going cross-platform than a year ago," he explained, highlighting that developers who used to create software for Apple only are now branching out to make apps for Android too.

App Annie claims that the introduction of the iPhone 5 and iPad mini towards the end of 2012 led to an increase of about 20 per cent in App Store sales between October to December. Apple's App Store growth rate didn't match Google's last year, but it did grow more in absolute revenue because of the larger customer base, said the research firm.

A recent change in the presentation of Apple's financial results revealed that Apple now makes more revenue from its iTunes, software and services than it does from iPod sales. Overall, Apple says that it has generated more than $7 billion from the App Store since its launch in 2008, with a total of more than 800,000 apps now available for iOS.

Google Play now also boasts about 800,000 apps, and could overtake Apple to reach the million app milestone first, but ReadWrite claims that it doesn't matter, because iOS apps in Apple's App Store are still better quality than their Android counterparts.

Application testing company uTest has released a new 'Applause' service, which crawls all live apps in the App Store and Google Play to determine each app's quality by aggregating rankings and user reviews.

Apps are given an Applause score between 1 and 100, and then average scores for app categories can be compared across operating systems. Overall, iOS ranks higher than Android in the majority of app categories.

uTest's Matt Johnston says that the company was looking for two properties when developing the algorithm for Applause. "We look for two things. One, did it have a statically different bearing on the perceived app quality, the level of user satisfaction. Second, did the keywords or key phrases that we are crawling intuitively fit into this bucket. So, for performance for example, there are really clean words like crash or freeze or hang."

Of course, how much we can rely on uTest's Applause algorithm to determine quality of apps is debatable, especially when considering that the test searches for key words, but may not be able to determine the context of the comment. Applause does, however, have the ability to exclude certain comments in the case of astroturfing or black hat review tactics.

But the quality of apps also comes at a cost, with new data from Consumer Intelligence Research Partners (CIRP) revealing that iPhone users rack up the highest average monthly carrier bill among all smartphone owners.

"We think it has to do with their data plans and carriers, rather than their usage habits," says CIRP co-founder Michael Levin. "They are all on expensive data plans, unlike Android users, some of which are on prepaid or unsubsidized plans with regional carriers."

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