The result is shown in columns D, E and F of Figure 1. We start out by creating a frequency table with bin size of 3 and a maximum bin of 12, as described in Frequency Tables. We now show how to create the histogram with overlay for the data in Example 1 of Using Histograms to Test for Normality. Second, we need a way to scale the normal curve so that the areas match. First, to place the two graphs on the same chart we can’t use a bar chart for the histogram instead, we need to use a scatter plot.
There are two complications with this approach. In this approach, we create a histogram and then add to this chart a normal curve whose area under the curve is the same as the area of the histogram.
