Frequency Capping: Is there a case for Search?

I attended an inductory session on display advertising today, courtesy of Tribal Fusion. Despite working with search, price comparison and affiliates for many years, I’ve had virtually no exposure to display. I always considered it quite a simple science compared to search, but now I appreciate the range of technology available I’ve started to rethink a little!

One particular feature that caught my eye was frequency capping. A frequency cap denotes the highest number of times you want a particular ad to be shown to one user – so are you happy for Joe Blogs to see your ad every time they visit hotmail.com, or would you like to limit him to just three ad views and save your valuable impressions for newer viewers? Is your campaign direct response (in which case the chances of a conversion after a number of views declines rapidly), or is it branded (in which case there’s an argument that repeated exposure is good thing)? Are you worried about overexposing your brand to your target audience?

I was thinking about how this relates to search advertising – would there be a case for frequency capping within search results? You’re not paying by impression, so if a user views your PPC ad many times you don’t care (unless you’re really worred about CTR). You are paying by click though – what if someone clicks on your ad more than once? How often is too much? What if they convert every time? Imagine if you could say “if someone clicks on my PPC ad 5 times in 30 days and still does not convert, I’m not interested any more”, would that work?

Paid search, of course, is very different to banner. If someone is exposed to your ad on Hotmail then there is no conscious decision involved on their part. If someone clicks on your ad in the search results then they’re making a conscious decision to visit you and interact with your brand or site. A user clicking multiple times could just be a loyal customer – after all, we know that many searchers will come back to your site again and again through the route that they originally found you. If you remove that method, you may end up losing people who eventually would have converted.

But what about visit 15? Or visit 50? Surely there’s a point at which the conversion rate declines to the extent that the click is no longer valuable to you? How many clicks would this remove, and how many dollars would this save? How much would it cost Google to implement?

I don’t think its a cut and dry case – it would be interesting to research further. At the very worst it could be a good gimmick that would encourage advertisers to put Google Conversion Tracking on their site.