ROI stands for Return on Investment, and is a derived metric that captures how effective your media investment was.
It looks at:
(a) the positive value associated with the user performing the desired action (for instance, making a purchase, where the positive value is the money they spent)
(b) the cost of the media
(c) the cost of goods sold (the cost associated with the product.
As you can tell, Return on Investment (ROI) is related to Return on Ad Spend (ROAS), but also adds the cost of the product in the calculation of the derived metric. Because Attributed ROI is a derived metric, attributed credit is not directly distributed to it. Rather, Attributed ROI is calculated using Attributed Revenue.
The formula used is:
Attributed ROI = Attributed Revenue / (Media Cost + Cost of Goods Sold)