Assessments of research groups by expert panels are commonplace. A conceptual distinction between nationwide evaluations, approaches fitting within a national framework, and approaches fulfilling a national, regional, or local regulatory requirement can be made. Few papers exploit the wealth of the data made available to panels: most analyses and discussions focus on the relation between assessments scores and bibliometric indicators. However, expert panels are expected to take other information such as funding and PhDs into account as well. Using a data set on 52 science research groups that have been evaluated in view of an on-going series of research assessments at the University of Antwerp (Belgium), we build cumulative logistic regression models that explain the assessments of research group quality and productivity. In addition to the discipline, the predictors in the models explaining quality and productivity are group size, h-index of the group leader, and efficiency in terms of publishing in top journals. Strikingly, the same predictors apply in the model for quality and in the model for productivity.