Just how much are you paying for ‘free’ apps on your phone? You’re potentially forking over a lot of your personal data, according to researchers at Cambridge. A new study has shown that a majority of phone applications compile personal information, sending it over the internet without consulting the user. Surely an unsettling thought for the procrastinating student – though perhaps an incentive not to take a study break with a quick round of Angry Birds.

Phone apps sometimes collect data for legitimate reasons, for example to provide adverts better-targeted to the app user, or to collect geographic data about the regions where the application is most widely used. But the quantity and accuracy of stored information could cause worry to people who use the app; in the worst cases, applications were found to have unfettered access to the messages and contacts stored on the phone.

The academics behind the research, who studied over 250,000 applications available on the Android Market, found that 70% of free apps collected personal data beyond that they needed to function. In the comics category, as an example, over a third collected detailed information about the phone’s location.

The majority of data collected to provide targeted advertising, and is sent to advertisers. But Dr Ilias Leontiadis, one of the researchers, explained that the creators of the app are responsible for deciding the types of data that it collects and sends. Describing the problem, he said: “You don’t know if the data is for the app or the advertiser, and you don’t know how it would be used.”

Targeted ads are indispensable as the main source of revenue for free apps, so cutting off access to all data is not realistic. One of the proposed solutions is to separate out data into that used by the app, and that sent to the advertiser.

 In this way, users would know that their data is only being used to provide these ads – but it raises questions over whether the ad company can be trusted. “There are over 52,000 developers in the market, but only eight big ad networks,” points out Dr Leontiadis. “It’s easier to control those networks than those developers.”

If your personal data is the true price of ‘free’ apps, it appears that it is also a hidden charge on the ones you pay for – the researchers discovered 40% of paid applications also collected “sensitive” information for no apparent reason.

 “I can see why companies would want to collect data about who’s using their app,” said Robinson student Louis Tam, looking up from his iPhone. “But I don’t think that they should be collecting personal information, like your contacts.”