Question

How does the outlier affect the standard deviation in the following set of data?

9 9 10 10 12 15 16 16 17 17 17 20 23 28
5.32
Removing the outlier lowers the standard deviation by 1.09
No outlier
4.23

Answer 1

Removing the outlier lowers the standard deviation by 1.09

Explanation:

Find the standard deviation of the data WITHOUT the outlier first.

If you don't know how to do standard deviation, here are the steps:

1. Find the mean

2. Subtract the mean by the data set values

3. Square the differences

4. Add the squared numbers together and divide by the number of data set values

5. What you have now is the variance, and all you have to do now is square the variance and you have the standard deviation

Repeat this, but WITH the outlier this time.

Final step, just subtract the smaller number (answer you got from the data with the outlier) by the greater number (answer you got from the data without the outlier) and you have your answer: 1.09!