Like any other business department, the marketing team is often assigned limited resources to do its function.
As a result, it ultimately ends up being a numbers game: did the marketing team generate sufficient ROI with the restricted amount of money they had? And if you could re-allocate those resources in a particular way, could they have gotten the company more bang for the buck?
The Devil is in the Detail
While maximizing a budget for ROI seems like a straightforward concept, the devil is all in the detail. In the marketing world, ROI is a subjective term – no one agrees what it means, how to measure it, how to develop a strategic plan around it, or what tactics to use. Not surprisingly, it’s within these fuzzy parameters that most marketing decisions and mistakes can be found.
Source: http://www.visualcapitalist.com/5-big-marketing-budget-mistakes-avoid/