According to Ad Age (7/18), there are ways to measure the effectiveness of dead celebrities as spokespeople for a company's advertising:
"In its latest 2005 Dead Q tallies, Lucille Ball, Bob Hope and John Wayne top the list of the public’s favorite dead celebrities. Although Elvis was Forbes’ top-earning dead celebrity, he ranks at No. 12 on the Dead Q list. Also among the top 15 are Jimmy Stewart, Katherine Hepburn and the Three Stooges.
"Two recent deaths made this year’s Dead Q list: Johnny Carson, who is ranked No. 7, died Jan. 23, and John Ritter, who is ranked No. 8, died Sept. 11, 2003."