Chapter 4: Variability

Variability Explained Without Math
 Why Measure Variability?
 The Range

Variance and Standard Deviation
 Deviations From The Mean
 The Variance (to the rescue!)
 The Standard Deviation
 Recap
 Example  Deviations From The Mean
 Example  Variance
 Example  Standard Deviation (plus checking your answers)

All the Essential Formulas
 Sum of Squares  Computational vs Definitional Formulas
 Sample Variance and Sample Standard Deviation

Understanding the Standard Deviation
 Using the Standard Deviation to Visualize a Distribution
 What is a Biased Estimator?
 How Changing the Data Affects a Standard Deviation
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