The next thing we need to look at to properly read the plot is the key. Lets look at our example again.

Scores of Our Last Math Test


9|2 = 92%

The key in this case is:

9|2 = 92%

What does the key tell us? It tells us, that in this case, the data we are looking at are percentages. It is always important to know what you are looking at, and not just be a robot and read numbers off of a plot. Now that we understand the title and the key, we know that by reading the data off of our plot, we are reading off grades in percentages.