Bar Graph

In an experiment we may observe several categories such as ``round yellow'', ``wrinkled yellow'', ``round green'', or ``wrinkled green'' in the seed type of progeny in plant breeding. The number of observations in a particular category is called frequency.

In a typical bar graph the height of each bar represents the frequency of some category which is specified in the column of categorical values. The names of different category then appear on the x-axis (horizontal axis), and the frequency is located above the name of that category.