Return on investment (ROI) analysis prompted nearly half of advertisers and agencies to alter their 2005 media buying plans, according to a new study released Tuesday during the Advertising Research Foundation's annual convention in New York, reports MediaPost. Asked to rate each medium's delivery of ROI, cable TV was cited as best by 57 percent of the respondents, followed by network TV (54 percent) and online (45 percent).

The findings are the first from a series of planned studies conducted by the ROI Council, consisting of 16 leading agencies organized by Court TV. Some 75 percent of marketers and 59 percent of agencies said there would be a greater emphasis on measuring ROI in advertising in 2005.

The study also found that 44 percent of marketers and 31 percent of agencies "regularly or often" use some form of uniform ROI metrics to compare advertising across different media platforms.