i found this somewhere on a website :
Banner Ad Placement Study
This study assessed the impact of banner ad location on click-through
rates for webreference.com. The site caters to webmasters, providing
information on the creation and maintenance of web sites. Most of the
webreference's revenues come from the sale of advertisements (namely
banner ads) on their content pages. Therefore, it is essential that the
ads have a high click-through rate to stimulate future advertisement on
the site.
Several studies have been performed on other sites by independent
agencies to determine the role that elements of the ad (animation, etc.)
play in click-through rates. This study determines if location also plays an
important factor in the click-through rates.
Major Findings
1.Ads next to the right scroll bar (in the lower right-hand
corner of the first screen*) generated a 228% higher
click-through rate than ads at the top of the page.
2.Ads placed 1/3 down page, as opposed to the top,
generated 77% higher click-through rates.
3.Results from placing two ads on a page (at top and
bottom) were inconclusive.
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