MEPX
Chapter 5 of 13All chapters
  1. 1What analysis is for
  2. 2Types of data
  3. 3Collecting and sampling
  4. 4Cleaning data
  5. 5Describing the middle
  6. 6Describing the spread
  7. 7Choosing a chart
  8. 8Correlation
  9. 9Getting to causation
  10. 10Hypothesis testing
  11. 11Traps and paradoxes
  12. 12Tools of the trade
  13. 13Communicating results

Chapter 5 of 13

Describing the middle

Mean, median and mode.

Three different answers

The mean adds and divides. The median is the middle value in order. The mode is the most common value. On skewed data they can be far apart, and the choice is an argument you should be able to defend.

  • One extreme value drags the mean and leaves the median almost untouched.
  • Incomes and house prices are reported as medians for exactly that reason.

When an average misleads

An average hides everything about the shape. A room with two people earning nothing and one earning three hundred thousand has an average income of a hundred thousand and describes nobody.