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Chapter 4: Summarizing Data: Variability

Video Clips

Short video example of how to calculate the standard deviation (2:05).

This video discusses variability, range, interquartile range, semi-interquartile range, variance formulas, standard deviation, normal distributions, and an example (6:55).

This video provides an example of how to estimate the variance of a population by looking at the data in a sample (10:37).

This video illustrates the Empirical Rule and what it means when applying it to an example (4:59).

Audio Clips

This podcast describes range and standard deviation by discussing an example of students’ math scores (7:21).

An NPR interview discusses standard deviation as a “measure of abnormality” and how this is used to describe extreme climate change that the United States is currently experiencing (3:12).

Describes disproportionate impact suicide has on men and the group who has the highest rate of suicide (4:12).

Also includes link to the “Death Rates for Suicide by Sex, Race, Hispanic Origin, and Age: United States, Selected Years 1950-2010” table.

Web Resources

Provides description and example of how to calculate standard deviation.

An online simulation illustrates how changes in the mean and standard deviation affect the position and shape of the distribution.

This article describes interquartile range including what it is, how to find it, what it is used for, and its history. Also includes a video on the website that calculates an example.

This article provides a more in-depth explanation why the sample variance has n-1 in the denominator.