Why back when I first started to study business management the first thing we learned and the thing that was constantly drummed into our heads was the big O.  Each of our classrooms had the big O hanging in it so we would never loose track of the concept of What is the Objective?  As long as you remain clear on your objective it is easier to develop the steps to get there.   Eroi Email Marketing must have had the same teachers as they start out with their new clients in developing the objectives for the campaign.   When I discovered their approach I immediately had confidence in what they were doing.