Data are numbers with context. And the first job of the data analyst is
to put an often haphazard-looking list of numbers into a context. Doing
this requires summarizing the data. Summaries will by necessity attempt
to communicate the "essence" of a variable, but at the expense
of discarding other information. A good summary of the data will offer insight
into the central questions for which the data were collected and will guide
future analyses.
Reading
POD: Chapters 3 and 4
SMM:
Main
Concepts