date of manufacture. Or if the filtered data were from real estate, there may be property
address that is an attribute that is included as a key.
Fig. 9.1.14 shows that the data that are produced as part of the filtering process usually
contain uniquely valued attributes.
Fig. 9.1.14 Filtering raw data.One result of filtering is the production of subsets of data. In fact, when data are filtered,
the result is the creation of a subset of data. However, the analyst creating the filtering
mechanism may want to use the creation of a subset of data as an opportunity to prepare
for future analysis.
Stated differently, when a subset is created, it may be useful to put a little planning into
Chapter 9.1: Repetitive Analytics: Some Basics