This was originally proposed as an equation for social media on our blog post, Revisiting Metrics: Social Media Equation to demonstrate that metrics like links and traffic belong under reach not outcomes. However, it may apply to communication measures as well. Basic Theory: Intent vs. Outcome = Return On Investment (I/O = ROI) Supporting Equations: Intent x (value proposition + effective communication x reach) = Outcomes. Outcomes divided by Investment (budget + time + experience) = Return (cost per outcome). Additional definitions: Intent = business objectives + purpose of communication Outcomes = changed opinion/behavior (or sales, etc.) Any input, suggestions, etc. would be appreciated. I've been working on this for sometime and want to see where it might go. Conversely, I'm also interested in alternative equations worthwhile to review?