Idea 20of 22Builds onAn outlier pulls the meanUse the mode for the most popular
Use the median when a value is far off
Which number describes most students when one is far off?
Today you'll discover
- why the mean can describe almost no one
- why the median stays fair
Think firstWeekly allowance of six students
Which number best describes a typical allowance here?
Decide first, then press Next. Count how many dots sit below the mean.
A line plot of six weekly allowances: dots at $5, $6, $7, $8 and $9, and one far off at $40, ringed. The mean's triangle sits at $12.50, past five of the dots; the median's dashed line sits at $7.50 among them. The last step shows minutes to get to school: 8, 10, 11, 12 and 45.
See the whole ideathe big idea and the key word, in one place
The big idea
When one value is far off, the median usually describes the data best.
In real lifeHouse prices on a street with one mansion, or wait times with one long delay: the median gives the fairer picture.
Easy to get wrongThe mean is not wrong here; it answers a different question. It is the equal share, not the typical student.
Key word
- best measure
- the measure that answers the question asked; when one value is far off, often the median
Ready to use it?
- Choose between the mean and the median when there is an outlier.