One reason the online brand advertising industry hasn't been able to catch up offline brand advertising – despite how much time consumers spend on line these days – is that many ad-buyers are trained to believe that if Web users aren't clicking on their banner ads, then their banner ads are being ignored.

This is stupid because people are very unlikely to click on banner ads. The people who do tend to be poorer and less educated.

A company called Solve Media – which places ads in CAPTCHAs – has put together showing just how rare clicks on banner ads actually are.