| Class interval | The size or width of the class
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| Class frequency | The number of observations in each class
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| Class midpoint | The point halfway between the upper and lower limit of a class
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| Cumulative frequency polygon | A graph that shows the number of observations below a certain value
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| Frequency distribution | A grouping of data into categories showing the number of observations in each mutually exclusive category
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| Frequency polygon | A graph that consists of line segments connecting the points formed by the intersection of the class midpoint and the class frequency
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| Histogram | A graph in which the classes are marked on the horizontal axis and the class frequencies on the vertical axis. The class frequencies are represented by the heights of the bars and the bars are drawn adjacent to each other
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| Relative class frequency | Shows what percent each class is of the total number of observations (frequencies)
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