A new study from WebSideStory finds almost identical conversion rates for both organic and paid search.

The study tracked the traffic and conversion data from 20 business-to-consumer e-commerce sites during the first eight months of 2006, finding that paid search had a median order conversion rate of 3.4 percent, compared to 3.13 percent for organic search, ClickZ reports. There is supporting evidence for the effectiveness of both methods, Rand Schulman, WebSideStory's CMO, told ClickZ.

"On the one hand, because you control the message of paid search, you'd expect higher conversions," he is quoted as saying. "On the other side, because people value the 'editorial integrity' of organic, you'd expect higher conversions. Ultimately you need to do both. I think the eye-opener here is that neither side has a significant edge."

Wereas paid search gives advertisers more control over the ad's message, organic search results are viewed as more "independent", which can result in more clickthroughs, the study also found.