Often times while measuring an online advertising (Display/Online Banners) campaign only post-click activities or revenue are attributed to the campaign. One more factor which gets missed out is the post-impression activities and revenue.
Just to clarify the differences in post-click and post-impression, post-click activities are those which are the actions taken by consumers after they clicked on the Ad. Often times, consumers just view the ad and do not click on the ad but later on go to the website and take the action – this has been termed as Post-Impression activities.
I believe that the post-impression attribution should be higher for campaigns which are more branding as opposed to direct response. Post-impression action happens when the ad leaves an impression in consumers mind and the consumer comes back later to the site and takes the action. Thus, shows increase in brand awareness of the product. When the consumer clicks on the ad, that indicates that the consumer engaged with the brand and then took action.
There are many ways of calculating the post-impression attribution i.e. what percentage of the post-impression activities should be attributed to the campaign. One of the ways is to create a test and control group. For the control group, it needs to be made sure that they are not exposed to the Ad. The next step should be to see how many post-impression actions are taken by the control group. The lift in the conversion rate (post-impression actions/impressions) in the test (group exposed to the Ad) and control group is the post-impressions attribution. Essentially, in this methodology the control group conversion rate is the rate at which the consumers would convert with no exposure to the test Ad.
Similar methodologies have also been used in the past to establish the effect of marketing in retail stores.