Chapter 03 - Descriptive Statistics: Numerical Measures

The interquartile range (IQR) is just the difference between the first and third quartile. Formulas for first and third quartile. Different sources compute the quartiles slightly differently. Excel computes the first quartile as observations number (n +3)/4 in the sorted list of n observations, while your text uses observation number (n+1)/4. ................
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