Idea 17of 22Builds onA value far from the restAdd, then divide by how manyThe median: the middle value in order
An outlier pulls the mean
What happens to each measure when one value jumps?
Today you'll discover
- which measure moves
- which ones stay put
Think firstBus waits: 4, 5, 5, 6, 5 minutes
If Friday's wait becomes 20 minutes, which measure changes the most?
Decide first, then press Next. Watch which marker moves when the dot slides.
A line plot of bus waits 4, 5, 5, 6 and 5 minutes, with mode, median and mean all at 5. Friday's dot slides from 5 out to 20, leaving a hollow mark labelled was 5. The mean's triangle moves to 8; the median line and the mode box stay at 5. The last step shows quiz marks where a 7 became 0.
See the whole ideathe big idea and the key word, in one place
The big idea
An outlier pulls the mean towards it; the median and the mode hardly move.
Before and afterWaits 4, 5, 5, 6, 5: mean 5, median 5, mode 5. Change 5 to 20: mean 8, median 5, mode 5.
Key word
- pull
- how an outlier drags the mean towards itself: up if it is high, down if it is low
Ready to use it?
- Say which measure an outlier changes, and by how much.