  How do analysts think about grouping and spatial operations? This overarching
question incorporates a number of points for investigation, including
understanding how analysts begin to explore a dataset, the types of
grouping/spatial structures created and the operations performed on them, the
relationship between grouping and spatial structures, the decisions analysts
make when exploring individual observations, and the role of external
information. This work contributes the design and results of such a study, in
which a group of participants are asked to organize the data contained within
an unfamiliar quantitative dataset. We identify several overarching approaches
taken by participants to design their organizational space, discuss the
interactions performed by the participants, and propose design recommendations
to improve the usability of future high-dimensional data exploration tools that
make use of grouping (clustering) and spatial (dimension reduction) operations.
