Topic: Center, Spread and Position

Why the Mean Minimizes Squared Deviations

Why the Median Minimizes Absolute Deviations

Weighted Means from Frequency Tables

Variance and Standard Deviation Units

The Mean as a Balance Point

The Interquartile Range as Middle-Half Spread

Standard Deviation from a Frequency Table

Sample Variance and the N Minus One Convention

Recovering an Observation from Its Z Score

Quartiles by the Median-of-Halves Method