If you're planning to hold off on spending US$ 0.99 for a mobile app to get the free version instead, you might want to think twice. Research from Purdue University and Microsoft has determined that free mobile applications that use third-party services to serve and display ads are likely to drain batteries faster than their paid counterparts.
The study was done in partnership between Microsoft and Purdue, and resulted in a paper entitled "Fine Grained Energy Accounting on Smartphones with Eprof." Eprof is a specially developed tool used to analyze 21 Android and Windows Mobile applications' power usage. The study likewise did an analysis of data use over a 3G connection for five popular Android applications, which include the stock Android web browser, Angry Birds, The New York Times, Mapquest and Chess Free.
The study did not include iOS applications, though.
The researchers found that in-app advertising can comprise as much as 65% to 75% of an application's energy consumption. In the case of Angry Birds, the core application processes only took up 18% of an application's energy needs. Third-party ad display, analytics and other related activities accounted for about 45%.
More than 50% of energy needs is consumed in what is considered the "3G Tail," or communication done between the app and the ad server in refreshing the ad and targeting the ad based on demographic and location, among other things. In Free Chess, meanwhile, 50% of energy use was for serving ads.
"Most of the energy in smartphone apps is spent in I/O, and I/O events are clustered, often due to a few routines," says the report, highlighting that much of the energy drain and data transmission are in non-essential activities.
It's Not Just the Ads
The research determined that it's not only advertising that eats up battery juice, but also analytics and user tracking. The New York Times app uses 15% of its power requirements for user tracking.
Mobile-web versions of CNN and rendering a straightforward Google search using the stock Android web browser uses about 16% of the app's power requirements for user-tracking. This additional power requirement might mean alternatives that compress or strip down content for faster transmission like Opera Mini could become a more favored browser to the Android default.
Researchers say that even though these "free" apps were cheaper than their paid counterparts, this cost saving is negated by the added power drain. Sometimes, a user even has to pay more in terms of the data usage incurred, especially those who are not on unlimited data plans.
Is There a Solution?
The researchers have offered a solution to the indiscriminate use of data and excessive power consumption by these supposedly free applications. In particular, the use of "bundles" of data was found to have reduced power consumption by 20% to 65% on the four applications tested. The Purdue and Microsoft researchers have proposed "bundles, a new accounting presentation of app I/O energy, which helps the developer to quickly understand and optimize the energy drain of her app."
Given the findings of this study it seems there's no free lunch, after all. While most users are aware that their free apps are supported by ads, it's now clearer that "free" might actually come at a higher cost, which comes in the form of additional resources expended in accessing these ads. As such, a one-time US$ 0.99 payment seems like a drop in the bucket compared to the potential cost of a drained battery and mobile data usage in the long run.