Free Ain't Easy

Warning: Actual Learning About Games Ahead. 

"[P]layers should be rewarded even if they don't pay to play, as we know their influence far surpasses their direct income generated and high value players are, of course, rewarded for their loyalty and commitment. Games that are able to respond to real-time player behavior will become the norm in the next few years and players will come to expect a level of support and interaction with the games they play, allowing them to progress further and take greater enjoyment from the experience."

- Games Analytics Whitepaper "The Science of Listening"

Although this whitepaper is focused on the free-to-play game experience, much of the analysis can, and should, be applied to boxed retail titles as well.

Link via Gamasutra