The five W’s: WHO, WHAT, WHEN, WHERE, and (if possible) WHY…and HOW
We must know at least the Who, What and Why to be able to say anything useful based
on the data. The Who are the cases. The What are the variables. A variable gives
information about each of the cases. The Why helps us decided which way to treat the
We treat variables in two different ways, as categorical or quantitative:
Categorical (qualitative) variables identify a category for each case.
Quantitative variables record measurements or amounts of something; they must have
Sometimes we treat a variable as categorical or quantitative depending on how we want
to learn from it.
Data: systematically recorded information, whether numbers or labels, together with its