Banner ads were initially judged primarily on the basis of click-through rate (CTR). In the early days of the Web, click-through rates were generally much higher than they are now, perhaps due to the novelty factor. Other causes for the decline in CTR may include technical limitations, the awkward horizontal shape, poor banner design, an excessive percentage of run-of-network buys, and accumulated bad experiences of Web surfers.
“Banners never work” is a common refrain from the anti-banner crowd. Although click-through rates have gone consistently downward, the same can be said of banner ad prices. It is still possible to achieve a click-through rate many times the industry average by combining good placement and design. Combining below-average ad rates and above-average response rates can lead to an acceptable return on investment, just as in any other advertising medium.