ECO 329 Chapter Notes - Chapter 3: Unimodality, Frequency Distribution, Categorical Variable
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Stem-and-leaf plots can be used to describe the shape, center, and variability of a numerical data set, but they can become huge and complex if the number of observations is large. A summary table like a frequency distribution for categorical data would be helpful. But when the data set is numerical, there are no natural categories. The solution is to use intervals as categories, or classes. We can then construct a frequency distribution for continuous data and a histogram. Frequency distribution: a summary table that displays classes, frequencies, relative frequencies, and cumulative relative frequencies: how to construct a frequency distribution for numerical data. Choose a range of values that captures all of the data. Each interval is called a class, or class interval. The endpoints of each class are the class boundaries. An observation equal to an endpoint is allocated to the class with that value as its lower endpoint.
