• by Joe Mandese  @mp_joemandese, April 7, 2004

At a time when the top research posts have been left vacant at a number of major media shops, another top media researcher is leaving Madison Avenue. Gregg Liebman, senior vice president-research director at Zenith Media, has resigned to join Turner Broadcasting System as vice president of CNN Ad Sales Research. He replaces Sherrill Mane, who moves to senior vice president-market strategy for news reporting to Barry Fischer, executive vice president-market strategy.

Liebman's departure comes as top research positions remain unfilled at other big media agencies, including Omnicom's OMD and PHD units.

OMD is said to be close to filling its worldwide research post, which was left vacant when Andrew Green resigned to start a new research operation for U.K.-based media auditor Billetts.

The depletion of Madison Avenue's research talent pool comes at a time when marketers are asking their agencies to develop even more sophisticated and strategic research to improve the effectiveness and efficiency of targeting their advertising messages, in many cases, beyond traditional media.

At Turner, Liebman will oversee research and analyses for all of the CNN News Group's advertising sales efforts, including CNN, Headline News, CNNfn, CNN.com, and other CNN-branded news networks.