A Guide for Measuring the ROI of Gamification
Measuring ROI is an elusive task: you have external factors that affect the results; measuring the baseline is a subjective process; forecasting future impact is hard and even calculating the actual investment is a project by itself.
That said, one can measure almost anything (I recommend reading the book How to Measure Anything). There are testimonies of increased sales results after implementing gamification systems by 5-15%. But, I believe we need to dive in to understand how to analyze success.