Recent R&D efforts for the U.S. Intelligence Community have been directed towards providing new Information Technology that better supports collaborative war-gaming and decision-modeling among expert teams so as to produce valid and reliable intelligence in a more-timely, less-costly manner. This paper describes Schemer, a web service that provides knowledge validation and collaboration support to virtual panels of experts. Of particular interest is the way that Schemer uses visualization of knowledge distribution among panelists to motivate collaboration, with the goal of fostering greater consensus and knowledge-building, hence, better intelligence. Since an additional requirement for supporting virtual panels is incremental data acquisition from panel members, models must often be computed from incomplete data. The same visualization techniques for evaluating consensus formation and knowledge-building among panelist also prove useful for evaluating the impact of data imputation on model validity and reliability.