2D Histograms - Hanging Bars

The hanging bars histogram offers a "visual test of normality" of the distribution that helps identify the areas of the distribution where the discrepancies (between the observed and expected normal frequencies) occur. While the standard way of presenting the normal distribution fitted to an observed distribution is to overlay the best-fitting normal curve over a histogram, the hanging bars histogram does just the opposite: it suspends the bars representing the observed frequencies for consecutive ranges of values from the best-fitting normal curve. If the investigated distribution can be well approximated by the normal curve, the bottoms of all bars should form a straight, horizontal line. If more than one variable is selected, then one graph will be produced for each variable selected.

See also, 2D Histograms and Graphs - 2D Histograms.