The study mostly shows that the media let the administration frame how the situation was reported.
"This study supports four major findings about the media’s coverage of WMD during the three periods: 1. Most media outlets represented WMD as a monolithic menace, failing to adequately distinguish between weapons programs and actual weapons or to address the real differences among chemi-cal, biological, nuclear, and radiological weapons. 2. Most journalists accepted the Bush administration’s formulation of the “War on Terror” as a campaign against WMD, in contrast to coverage during the Clinton era, when many journalists made careful distinctions between acts of terrorism and the acquisition and use of WMD. 3. Many stories stenographically reported the incumbent administration’s perspective on WMD, giving too little critical examination of the way officials framed the events, issues, threats, and policy options. 4. Too few stories proffered alternative perspectives to official line, a problem exacerbated by the journalistic prioritizing of breaking-news stories and the “inverted pyramid” style of storytelling. "
Which is fair, I guess. But still, most news outlets internationally were doubtful that Iraq had WMDs and were vindicated after the war.