Querying Web Site Visitor Trend Data with Coordinated Nested Bar and Pie Charts

Bar charts and pie charts are traditional ways of displaying trends and proportions in a data set. However, static charts don't scale well. We introduce a technique which does scale, an interactive browser design which uses aggregation and zooming to support bar and pie charts with thousands of items. Further, once a chart has many elements a user needs to be able to explore subsets of the data. We use a second view of the data, shown as a second chart as a scalable filter for selecting subsets. We present our design and its implementation in the SGViewer tool, and demonstrate with visit data taken from a web site log.