The exact use of histograms is to assess the probability distribution of a given variable by plotting the frequencies of observations occurring in certain ranges of values. They were first described by Karl Pearson. In their most simplistic form, histograms plot the frequency of a variable in a range of values called bins. We have chosen to start this chapter by describing histograms as they are the simplest of graphs that only accommodate one variable. Adding a density curve makes them a bit more informative but let's start with the basic form of the histogram. We will use the Class dataset that has been extensively used in the previous chapters:

Proc SGPLOT Data = Class;  Histogram Height;  Title 'Height of children in class across ...

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