How Is the Class Midpoint Calculated?

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The class midpoint, or class mark, is calculated by adding the lower and upper limits of the class and dividing by two. The class midpoint is sometimes used as a representation of the entire class.

A class midpoint is halfway across the interval of a class, hence it is calculated by averaging the lower and upper limits. One Kobo provides an example of calculating the class midpoint; in a distribution where class intervals range in values: {1 to under 3, 3 to under 5, 5 to under 7, 7 to under 9, 9 to under 11, 11 to under 13} the class midpoints would be {2, 4, 6, 8, 10, 12} respectively. Each of these values are the average of the low and high extremes of each respective class.