Lecture Data ans statistics Applications in Business and Economics

Crosstabulations and Scatter Diagrams
Thus far in this chapter, we have focused on tabular and graphical methods used to summarize
the data for one variable at a time. Often a manager or decision maker requires tabular and
graphical methods that will assist in the understanding of the relationship between two variables.
Crosstabulation and scatter diagrams are two such methods.
Crosstabulation
A crosstabulation is a tabular summary of data for two variables. Let us illustrate the use
of a crosstabulation by considering the following application based on data from Zagat’s
Restaurant Review. The quality rating and the meal price data were collected for a sample
of 300 restaurants located in the Los Angeles area. Table 2.9 shows the data for the first 10
restaurants. Data on a restaurant’s quality rating and typical meal price are reported. Quality
rating is a categorical variable with rating categories of good, very good, and excellent.
Meal price is a quantitative variable that ranges from $10 to $49.
A crosstabulation of the data for this application is shown in Table 2.10. The left
and top margin labels define the classes for the two variables. In the left margin, the row labels
(good, very good, and excellent) correspond to the three classes of the quality rating variable.
In the top margin, the column labels ($10–19, $20–29, $30–39, and $40–49) correspond to


Descriptive Statistics: Numerical Measures

Numerical measures of location, dispersion, shape, and association are introduced. If

the measures are computed for data from a sample, they are called sample statistics. If the
measures are computed for data from a population, they are called population parameters.
In statistical inference, a sample statistic is referred to as the point estimator of the corresponding
population parameter. In Chapter 7 we will discuss in more detail the process of
point estimation.
In the three chapter appendixes we show how Minitab, Excel, and StatTools can be used
to compute the numerical measures described in the chapter.