WebSideStory has given the Search Marketing world a gift in the form of study results showing similar conversion rates between paid search and organic search. This gives us a metric with which to measure the ROI or cost of acquisition of organic search. This will still be a guess as to how much affect optimization has on search traffic but it justifies any increased spending on optimization in my humble opinion. I believe that results would differ if we were talking about advertising to internet/technical savvy searchers, who are more likely to click on organic than paid because they are not shopping for themselves but for their companies.
"Paid Search Has Only Slight Edge in Conversion Rates Over Organic Search, According to New WebSideStory Study"
"WebSideStory, Inc. (Nasdaq: WSSI), a leading provider of digital marketing and analytics solutions, today announced the results of a new study that shows paid search has only a slight 9 percent edge in conversion rates over organic search. In a study of leading business-to-consumer (B2C) e-commerce sites during the first eight months of this year, paid search -- keywords bought on a pay-per-click basis at search engines such as Google, Yahoo and MSN -- had a median order conversion rate of 3.40 percent at business-to-consumer e-commerce sites using the company's award-winning HBX Analytics technology. This compared to a conversion rate of 3.13 percent for organic search results, defined as non-paid or natural search engine listings, during the same January-to-August timeframe, according to the WebSideStory Index, a compilation of e-commerce, site search and gloobal Internet user trends. The study analyzed more than 57 million search engine visits. Order conversions occurred during the same session. "