How to Clearly Label the Axes on a Statistical Histogram

By Deborah J. Rumsey

The most complex part of interpreting a statistical histogram is to get a handle on what you want to show on the x and y axes. Having good descriptive labels on the axes will help. Most statistical software packages label the x-axis using the variable name you provided when you entered your data (for example, “age” or “weight”). However, the label for the y-axis isn’t as clear. Statistical software packages often label the y-axis of a histogram by writing “frequency” or “percent” by default. These terms can be confusing to others who have not studied statistics (unlike yourself): frequency or percentage of what?

Clarify the y-axis label on your histogram by changing “frequency” to “number of” and adding the name of what the y-variable is referring to. To modify a label that simply reads “percent,” clarify by writing “percentage of” and the name of what the y-variable is referring to.


This example shows a histogram of ages of the Best Actress Academy Award winners. Notice that the y-axis is clearly labeled as “Percentage of actresses in each age group.”