Nevada tourism officials for decades have developed advertising catch phrases and created campaigns and compared the effectiveness of advertising media.But for the first time ever this year, the Nevada Commission on Tourism is digging deep into newly commissioned research to develop an overarching brand identity for marketing the Silver State to visitors.Larry Friedman, interim director of the tourism commission, says the brand-development effort is a natural next step in the commission's effort to fine-tune the effectiveness of its marketing efforts.In recent years, he notes, the state has developed cost-effective strategies to deliver its advertising messages, largely through use of online …