PivotViz: Interactive Visual Analysis of Multidimensional Library Transaction Data

As public libraries become increasingly digitalized they become producers of Big Data. Furthermore, public libraries are often obliged to make their data openly available as part of national open data policies, which have gained momentum in many countries including USA, UK, and Denmark. However, in order to utilize such data and make it intelligible for citizens, decision makers, or other stakeholders, raw data APIs are insufficient. Therefore, we have developed PivotViz that is a comprehensible visualization technique, which combines parallel coordinates and pivot tables. It provides, a multidimensional visual interactive pivot table for analysis of library transactions -- loans, renewals, and returns of books and other materials across location and time. The paper presents the PivotViz technique and discusses its prospects based on implementations in two publicly available versions using open data from the two largest municipalities in Denmark. Examples of analysis results from these data illustrate the power of PivotViz.