[…] Many categories are easier to display. The previous example has five categories but imagine having 20 or 50 categories. A horizontal bar chart can display the category names in a straightforward manner just by making the chart taller. This is an advantage for graphs on the printed page (in portrait mode) and for an HTML page because it is easy to scroll a web page vertically. The graph to the right shows a portion of a horizontal bar chart that has 45 categories. Each category is the name of a pair of variables and the bar chart shows the Pearson correlation between the two variables. …