We are all used to use the term average in common speech. For example, in sports, you can hear that the players of a specific team are in average old. The average value somehow describe the cases you are talking about. For example, a higher income average for some group compared to other groups of people might mean that these are richer people. However, as you will learn very soon, the average by itself is not enough to give you a correct estimation of a group. Just one very, very rich person in the group mentioned could shift the average income far to the right on the scale, to the higher values, although all of the other people from that group might be quite poor.
Therefore, we need to measure more ...
