Chapter 2 Measures of Spread

Measures of spread, or measures of variability, tell us how spread out a distribution is. For example, consider the below two histograms:

By viewing the histograms, we can clearly see that the distribution of data in Histogram A is more spread out than the distribution of data in Histogram B. Measures of spread can help us to quantify these types of differences in variability. The measures of spread we will consider in this section are the variance, standard deviation, interquartile range, and range. We will also consider the concept of quartiles.

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These notes have been prepared by Amanda J. Shaker. The copyright for the material in these notes resides with the author named above, with the Department of Mathematics and Statistics and with La Trobe University. Copyright in this work is vested in La Trobe University including all La Trobe University branding and naming. Unless otherwise stated, material within this work is licensed under a Creative Commons Attribution-Non Commercial-Non Derivatives License CC BY-NC-ND