We report on our work towards understanding analytic rea soning processes in face-to-face collaborative analysis using visualization techniques. How analysts reason is an active topic of research and in our community we know even less about how a group forms an understanding, insight, and reasons about data. We report on our effort in capturing the richness of reasoning activities through mixed-method approaches and show how Pairgrams-a visualization of interactions with an analytics workspace by pairs of participants-helped us to understand collaborative analysis and reasoning