How to decide whether smartphone app should be free with ads or paid ($0.99) without ads?

Is there any data (such as from app downloads or consumer surveys) that would help a developer decide whether people (consumers) will be more likely to use (download/install) a smartphone app (iOS and Android) if it is free but has ads or costs $0.99 and is ad-free?

Let's assume that the app is moderately useful (not extremely useful but does provide an efficiency/productivity benefit for the 1-10 times it is used per month).

Thank you.

This is something we have done a lot of research into and there is loads about this which can be found with a quick search of Google.

General consensus is that free pays more in the long run as you get to critical mass much quicker - the utopia seems to be freemium with easy up sells and cross sells.

Here are some links I found useful:

http://www.bluecloudsolutions.com/blog/free-paid-apps-works/ http://techcrunch.com/2012/08/26/how-free-apps-can-make-more-money-than-paid-apps/ http://mashable.com/2011/08/17/price-mobile-app/