Once you have prepared a data file, you are ready to start
analyzing the data. The first step in data analysis is
describing the data. You look at the information you have
gathered and summarize it in various ways. You count the number
of people giving each of the possible responses. You describe
the values by calculating averages and seeing how much the
responses vary. You look at several characteristics together.
How many men and how many women are satisfied with your new
product? What are their average ages? You also identify values
that appear to be unusual, such as ages in the one hundreds or
incomes in the millions, and you check the original records to
make sure that these values were picked up correctly. You do not
want to waste time analyzing incorrect data. Sometimes you have
information available for everyone or everything that you are
interested in drawing conclusions about, and all you need to do
is summarize your data. But usually that is not the case.
Instead, you usually want to draw conclusio