Histograms
Histograms are another form of bar chart in which measurements are grouped into bins; in this
case each bin representing a range of values of some parameter. For example, in Figure 8, X
could represent the length of a rod in inches. The figure shows that most rods measure between
0.9 and 1.1 inches. If the target value is 1.0 inches, this could be good news. However, the
chart also shows a wide variance, with the measured values falling between 0.5 and 1.5 inches.
This wide a range is generally a most unsatisfactory situation.