Return on Investment is the basic calculation made to assess any investment, but too often gets complicated by all sorts of assumptions and forecasts.
In these days of rapid prototyping, access to A/B testing tools using the web, and the logic of many small bets in the innovation process rather than a few large ones, the calculation becomes less important if you follow the simple rule:
“Keep the “I’s” small, and nobody will bother you too much about the “R”