Just 20 per cent of people who download a free iPhone app come back to use it the next day, while after 30 days, just 5 per cent are still using it.

That's according to a study conducted by analytics firm Pinch Media. What's more, paid apps show a steeper decline in user interest.

It should be noted that the study relates to iPhone applications of all kinds, not just games. We wouldn't be surprised if games performed better.

Pinch also says free apps tend to be run 6.6 times more often than paid apps - 80 sessions - although CEO Eric Yardley explains to TechCrunch that the outlook for ad-supported apps is nevertheless somewhat murky.

In fact, he claims that less than 5 per cent of all apps would make more money now with ads than by charging for paid downloads. "Unless there is something inherent about the app that screams free, sell it."