ROI — Return on investment. What does digital signage do? It can advertise or communicate, and also entertain. For example, if your signage is deployed in a grocery store for the purpose of advertising a specific brand of goods, one should focus on the check-out lanes. Has the signage increased that brands sales? If so, by how much? That increase can be used to calculate ROI. You can also compare stores that don’t have signage with like stores in the same markets that do, that’s a precise measurement.