stat_mod_2.pdf

Summarizing Quantitative Data Using Tables & Graphs Section 2.3: Summarizing Quantitative Data Using Tables & Graphs In this section, we summarize quantitative data. We begin by considering frequency distributions of numerical, or quantitative, data. The most important difference between summarizing numerical data and non-numerical data is in the defining of the classes. In example 2.1 of the previous section, each class was clearly defined because each class (i.e. each car model), was independent of every other car model. That is, when one car was sold it was either a Ford or a Chrysler or a Nissan… In other words, a car cannot be a Ford and a Nissan. A car cannot be a Nissan and a Chrysler. Therefore, in example 2.1, there was no possible overlap of the data. Each car will fit into one and only one class. However, defining classes for numerical data is not as clear-cut. In fact, there are usually many ways to define classes for numerical data. Consider the data in Table 2.4: Table 2.4 shows the hourly wages of workers at a certain factory. How would one define the classes for a frequency distribution for this data? There are many possibilities. For example, one could make each class $ 5.00 wide such as in Table 2.5: One could make each class $ .50 wide such as in Table 2.6: