Describe the types of situations that produce sparse or dense data cubes. Illustrate with examples other than those used in the book.

What will be an ideal response?

would produce sparse data cubes. This would include sets of continuous
attributes where the set of objects described by the attributes doesn’t occupy
the entire data space, but only a fraction of it, as well as discrete attributes,
where many combinations of values don’t occur.
A dense data cube would tend to arise, when either almost all combinations of
the categories of the underlying attributes occur, or the level of aggregation is
high enough so that all combinations are likely to have values. For example,
consider a data set that contains the type of traffic accident, as well as its
location and date. The original data cube would be very sparse, but if it is
aggregated to have categories consisting single or multiple car accident, the
state of the accident, and the month in which it occurred, then we would
obtain a dense data cube.