Histograms show the distribution of data across the range of values. The range of values is evenly divided into n classes, or intervals. For each class, the number of data values falling into that interval is tallied. The result is a bar graph that shows the number of items per class or interval. This is useful for identifying the distribution of the data (e.g. normal or lognormal). To view the histogram, press Show Histogram on the Graphics menu.