The one that sticks out
An outlier is a value far away from all the others.
The youngest child
In Poovizhi’s family the heights are 170, 173, 165, 118 and 175 cm. One of them is very different from the rest.
Which height is very different from the others?
What this lesson covers
The idea
Outliers are values which significantly deviate from the rest of the values in the data.
The youngest child
In Poovizhi’s family the heights are 170, 173, 165, 118 and 175 cm. One of them is very different from the rest.
Which height is very different from the others?
- 170 cm
- 118 cm
- 175 cm
Spot the outlier
Look at each dot plot. Tap the dot that is far from all the others. If every dot is close to the others, press No outlier.
Far away from the rest
A value that is far away from the rest of the values is an outlier. It can be at the low end, like 118 cm, or at the high end, like 40 stories.
An outlier is not just the biggest or the smallest value. It has to be far from the others. Yaangba’s family has a tallest and a shortest member, but no outlier.
Outliers are values which significantly deviate from the rest of the values in the data.
Notes
Outliers are values which significantly deviate from the rest of the values in the data.
Check yourself
Heights of five friends in cm: 150, 152, 149, 151, 190. Which height is an outlier?
The values are 4, 5, 6, 7, 8. Is the biggest value, 8, an outlier?
Poovizhi’s youngest child is 118 cm tall and the others are 165 cm to 175 cm. What kind of outlier is 118?
The data are 20, 22, 21, 23 and 60. How much bigger is the outlier than the next biggest value?
Answer: 37
60 − 23 = 37.
- 149. It is the smallest, but it is very close to the others.
- 152. It is close to 150 and 151. It does not stick out.
- 190 — correct. Yes! It is far above the others, which are all between 149 and 152.
- Yes, because it is the biggest value.. Every data set has a biggest value. An outlier must also be far away from the rest.
- Yes, because it is the last value.. The place in the list does not matter. Only the distance from the other values does.
- No. 8 is close to the other values. — correct. Yes! An outlier must be far from the rest, not just the biggest.
- A high outlier, at the upper end of the data. 118 is smaller than the others, so it lies at the low end.
- A low outlier, at the lower end of the data — correct. Yes! 118 is much smaller than all the others.
- It is not an outlier. It is 47 cm below the next height, 165. It is far from the rest.