Here's another take on that perennial attribution question: did my display campaign drive some of that search volume and in turn, account for some of my sales? The answer, again, is most assuredly "yes."
We spoken about this before because study after study has shown the impact. Yet most of the retailers we talk to are still using last-click attribution, perhaps with a wink and a nod toward the effectiveness of their display ads. So it's worth sounding like a broken record. A healthy percentage of consumers will see an ad and rather than click on it, type a few keywords into their browser's search box and click on a paid search ad or an organic search result to visit the store. Even more will conduct a search some time after, having decided to check out the store when they saw the display ad.
Hit the source link for the details and percentages, but the evidence is solid. So what's an advertiser to do, short of investing in a sophisticated and expensive attribution modeling system? A good start is to take your internal measurable conversion model, and your vendor's model, and do some work together to decide what the goal for the program should be. Run some tests to better understand the true impact of display on overall site sales. Come up with a reasonable multiplier for either the internal or external ROI numbers and set some goals. Then you both have some clarity about campaign performance and can optimize against agreed-upon numbers.