Attribution Model Digital Marketing

Digital Marketers use Attribution Models to assign value to the different digital marketing channels and how much has led to the conversion target on their website.
It is not enough to say the last ad channel the user saw before converting was the sole reason for buying and therefore the cost per acquisition was simply the cost of that ad airing (the Single Touch model). For each user journey to conversion there are likely to be several channels, ads and site mentions seen by the user before his/her enters the website and converts, including remarketing advertising after the user leaves.
Each of these ads and site mentions needs to have a value assigned so that the cost per acquisition metric calculations are more accurate, ROI is correctly measured and marketers have the right data to decide going forward the opimal mix of marketing activitiy to maximise revenue and future growth.