Overview of Using Data:
Definitions and Goals
are the facts and figures collected, analyzed, and summarized for
presentation and interpretation.
A characteristic or a quantity of interest that can take on different values is
known as a
is a set of values corresponding to a set of variables;
is the difference in a variable measured over observations (time,
customers, items, etc.)
The values of some variables are under direct control of the decision maker
(these are often called decision variables
a quantity whose values are not known with certainty is called a
variable, or uncertain variable
Types of Data
Data can be categorized in several ways based on how they are collected and the
In many cases, it is not feasible to collect data from
of all elements of interest. In such instances, we collect data from
a subset of the population known as a
a representative sample can be gathered by
Quantitative and Categorical Data
if numeric and arithmetic operations, such as addition,
subtraction, multiplication, and division, can be performed on them.
we can sum the values for Volume in the Dow data in
to calculate a total
volume of all shares traded by companies included in the Dow.
operations cannot be performed on the data, they are considered
We can summarize categorical data by counting the number of
observations or computing the proportions of observations in each category.