Graphs and Graphing (Encyclopedia of Science)
A graph is a pictorial representation of a set of data. These data can be of two distinct types: continuous or discontinuous. An example of continuous data would be temperature readings taken during a single day. A person may choose to observe and record the temperature once every hour, once every half hour, or on some other schedule. But temperature is a continuous phenomenon. One can read a temperature at any instant of any day.
Other data are discontinuous. Suppose you want to record the number of children in a class who are right-handed or left-handed. Children can be either right-handed or left-handed. Of course, some children might be ambidextrous, that is, capable of using either hand. However, those three choices are the only possibilities. They constitute three distinct categories and are regarded, therefore, as discontinuous data.
Representations of discontinuous data
Bar graphs. Graphs that depict discontinuous data are common in the daily newspaper. Those graphs usually take one of three forms: bar graphs, picture graphs, or circle (pie) graphs. In a bar graph, the distinct categories to be represented are shown on the horizontal axis. For example, three regions might be marked off for "right-handed students," "lefthanded students," and "ambidextrous students." The number of cases belonging to each category, then, are...
(The entire section is 847 words.)
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