The measure of center that is most affected by outliers is the mean.
Let’s see an example:
Imagine we have these 10 test scores:
90, 85, 88, 92, 87, 90, 91, 89, 70, 100.
Now, if we find the mean (average), we add all the scores:
90 + 85 + 88 + 92 + 87 + 90 + 91 + 89 + 70 + 100 = 921.
Then we divide by 10 (the number of scores):
921 ÷ 10 = 92.1.
Now, let’s say the score of 70 is an outlier (much lower than the others). If we change it to a higher score, like 95:
90 + 85 + 88 + 92 + 87 + 90 + 91 + 89 + 95 + 100 = 917.
917 ÷ 10 = 91.7.
So, the mean changed because of the outlier, but the median and mode stayed more the same!
That’s why the mean is most affected by outliers!