E-Consultancy puts in to question the Cost Per Acquisition (CPA) measurement that all of us use to measure the performance of a particular online marketing campaign. They argue that an online sale results form multiple marketing interactions online like emails and searches, in addition to the paid ad medium, that need to be considered when measuring the CPA. Otherwise, we are not getting a true marketing return on investment measure, and over-valuing the paid ad medium. Lynchpin Analytics studied its client base and found on average that over 50% of online sales driven by banner advertising were reliant on earlier visits from other channels such as search and email. As with traditional marketing where integrating print, radio, outdoor, and PR are key to delivering a high impact campaign, so is with the digital marketing mix. Not understanding the relationship between online mediums in delivering a sale, can lead to misguided decisions when evaluating your marketing campaigns.