The purchasing decisions taken by the customers are more often the result of online reviews and various comparisons. After buying products they themselves become reviewers and express their views on web about the product. This significantly impacts the reputation of the product and hence the company. This expands marketing horizons, thus its measure can't be only limited to ROI (Return on Investment). Work of marketers is not limited to being just creative. It is important for them to be contributing employees to the organization. Testing of the marketing strategy should be done. All the influencing factors should be kept in mind. The marketing team should be aware of when to measure. Read more at: http://bloomreach.com/2016/01/measuring-marketing-roi/