there was no correlation between those who clicked on an ad and those who purchased down the line through a view-through conversion. The problem with viewthrough In measuring view-based conversions, there is room for manipulation. Because viewthrough conversions are tied to the setting the ad network's cookie and later matching it up via the same ad network's page tag loaded on a conversion page, less scrupulous ad networks have taken advantage of this by purchasing cheap below-the-fold ad inventory more for the purposes of dropping as many cookies as possible across as many users as possible than for showing the target audience advertiser's ads. Such a strategy is called cookie-bombing and permits ad networks to potentially take credit for more conversion events than they should. When possible it is always recommended to use a standalone analytics package though many ad networks offer this functionality and to also leverage experimental design to measure true incrementality. See also Banner Ad - Display Banner Ad CPM - Cost Per Mille CPI - Cost Per Impression PPC - Pay per click CPA - Cost Per Action Cost per lead - Cost Per Lead Attribution (marketing) - Attribution Ad serving Click fraud Cost Per Click Web analytics Advertising network Demand-side platform Display advertising Behavioral targeting References External links Lilypad White Paper 1997 DoubleClick Continental Airlines Viewthrough Study 2004 Natural Born Clickers Update 2009 Viewthrough Measurement Consortium IAB Recognizes Viewthrough, Attempts First Definition Online advertising