@article {17149, title = {Exploration of Large Online Data Tables Using Generalized Query Previews}, journal = {University of Maryland Computer Science Technical Report (June 2001)}, year = {2001}, month = {2001///}, abstract = {Companies, government agencies, and other organizations are making their data available to the world over the Internet. These organizations often store their data as large online relational database tables. Users query these databases with front-ends that mostly use menus or form fillin interfaces, but these interfaces rarely give users information about the contents and distribution of the data. This situation leads users to waste time and network resources posing queries that have zero-hit or mega-hit results. Generalized query previews form a user interface architecture for efficient browsing of large online databases by supplying data distribution information to the users. The data distribution information provides an overview of the data. Generalized query previews give continuous feedback about the size of the results as the query is being formed. This provides a preview of the results. This paper presents the generalized query previews user interface architecture and our experimental findings. Our user study shows that for exploratory querying tasks, generalized query previews speed user performance and reduce network load. Categories and Subject Descriptors: H.5.2 [Information Interfaces and Presentation]: User Interfaces - Graphical user interfaces (GUI), H.3.5 [Information Storage and Retrieval]: Online Information Services - Web-based services. General Terms: Design, Human Factors, Experimentation. Keywords: Visual Data Mining, Information Visualization, Graphical User Interfaces, Relational Databases, Database Querying, Online Databases, Dynamic Queries, Previews and Overviews.}, author = {Tanin,E. and Shneiderman, Ben} }