Chapter 13: Connecting the Dots
When you have a list of numbers , test scores, daily temperatures, prices , it is rarely useful to look at every number individually. You want a single number that summarises the list. That summary is called a measure of central tendency.
There are three classic measures: the mean (average), the median (the middle value when sorted) and the mode (the most frequent value). Each tells a slightly different story.
In this chapter you will compute all three for various data sets, and learn when each is the right choice. You will also see how outliers (extreme values) can pull the mean far away from the typical value, while the median resists this pull.
These ideas , mean, median, mode , are at the heart of modern statistics, used by governments, doctors, sports analysts and YouTubers alike.
What's inside
- Mean (arithmetic average) , sum divided by count.
- Median , the middle of sorted data.
- Mode , the most frequent value.
- Comparing mean, median and mode , when each is best.
- Reading and interpreting data , tables, lists, real situations.
Key results
| Measure | How to compute |
|---|---|
| Mean | |
| Median (odd ) | The middle value after sorting |
| Median (even ) | Mean of the two middle values |
| Mode | The value(s) appearing most often |
Outliers pull the mean a lot; the median is more robust.
How to read this chapter
Always sort the data first. Mean, median and mode all become easier , and the patterns become visible.