The study, by researchers at WebSideStory Inc., found that search sites produce more than twice the conversion rate of many other Internet marketing efforts. The study defines conversion rate as the percentage of visitors to a site who view an ad or clicking on a search result and purchase a product or service.

According to the research, search sites had a conversion rate of 2.3%, meaning that for every 100 consumers clicking on a search result or advertisement, 2.3 people made a purchase. Online banner ads, shopping search sites and other online marketing efforts had a conversion rate

of 0.96%, the study found.

Consumers who went directly to a company' site without using a search engine - perhaps because they set a bookmark - had a much higher conversion rate of 4.23%.

Businesses have showered so much attention on search engines over the past several years because they are successful at producing buyers, WebSideStory said.

The study collected data from Web sites that sell apparel, toys, electronics, sporting goods and leisure products. Among the most successful were toy sites. When reached through a search engine, they had a conversion rate of 4.85% while Web sites selling computers and electronics had a conversion rate of 1.35%, the study found.