Paul Laberge continues his series of developer articles on Microsoft's Canadian Developer Blog with a look at one of the unsung heroes of the Windows Phone Marketplace - the ability to have trial applications that can easily be upgraded to the full paid-for version. Here's the kicker... Laberge reckons that adding trial support will increase sales by seven times.

The argument is anchored by two key statements:

1. Trial/free application get recieve more downloads than posting just a "paid for"version. The study quotes a seventy-fold increase.
2. The conversion rate of trial app downloads to purchases is ten percent.
3. Therefore, adding a trial version to your app should see more downloads, more conversions, and seven times more sales than simply putting an application up for sale.

It's unlikely that these numbers will fit every application exactly (and Laberge has not given us any 'workings' on how the numbers are derived) but I have to say that it's common sense that adding a trial helps sales. What surprised me is that conversion rate of 10%, as I thought it would be much lower!

Laberge goes on to talk about the different models you can use to create a trial application (reduced functionality, adding advertising and time limits are three suggestions) and links to code to add thees into your own projects.

Definitely one for developers to bookmark, and let's have the trial app mode not just as something we expect to see, but something we are proud to show off - "Windows Phone, where you can try everything before you buy" works for me!