The Burbank-based search marketing division of Yahoo! is launching a new model of ranking placement of online ads beginning Feb. 5, the company announced Wednesday. The new method combines keyword bid price with ad quality based on its historical performance to provide more valuable customer leads to advertisers and more relevant search experience to users. The old model of ranking had been based on bid price with the higher the bid the higher an ad appears in search results. The new quality-focused ranking model unlocks the full potential of Yahoo!’s search marketing network, said Yahoo! Inc. CEO Terry Semel. “With this important pieces in place our new search marketing system allows Yahoo! to more effectively connect to people with the businesses, products, services and information they are passionate about,” Semel said, in a statement.