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# Interquartile Range

An interquartile range is a statistical measurement that defines the middle range of numbers in a distribution and can be used to approximate the most common scores. In statistics quartiles are numbers that divide a distribution (a range of numbers) into quarters. It is a way to show how common particular numbers are in regards to where they fall in the distribution. Quartile 1 is the lower 25% of scores, Quartile 2 is 50% of the scores, and quartile 3 is 75% of the scores (quartile 4 is not referenced because that would just be all of the scores).

The interquartile range is the scores that range from quartile 1 to quartile 3 and is a measurement of the middle 50% of the scores in a distribution. The middle 50% generally holds the majority of the scores and is a good way to get an estimation of an average score. The interquartile range is calculated by subtracting the first quartile score from the third quartile score.

History of Psychology
History of Psychology