A data dispute over Dr. Mehmet Oz’s work on heart bypass surgery research resulted in a 2003 ban from research, the Oz campaign has confirmed. Oz, a cardiothoracic surgeon, was scheduled to lead the 83rd annual American Association for Thoracic Surgery conference that year with an analysis of the effectiveness of a heart-lung machine in heart bypass surgery, but a last minute decision to widen the scope of the presentation resulted in the forced withdrawal of his work and a two-year ban from presenting with the association. “[Oz’s] team elected to broaden the scope of the work with more patients,” said a spokesperson for the Oz campaign. “Reviewers of his team’s work wanted only the data in the original paper to be presented, which created an academic disagreement amongst researchers.” But bans and suspensions from research aren’t something medical societies take lightly—they’re reserved for significant disputes, according to The Washington Post. “My understanding is it was the lack of really solid statistical analysis that called everything into question,” an anonymous source familiar with the ban told the outlet.