Tip: Interpreting the y axis in @RISK histograms

Q. In the histograms of my @RISK distributions and results, what do the numbers on the vertical axis mean? Can I make the scale more user friendly?

A. The default scale is probability density. This is adjusted so that the areas (height × width) of all the bars add up to 1.

You may prefer a relative frequency scale, where the height of each bar equals the proportion of the distribution that falls within that bar. To set relative frequency, click the histogram icon at the bottom of the window. See the blue highlight in this illustration:

Histogram showing probability density

A drop-down appears with your formatting choices. Select relative frequency — that's all there is to it!

Relative Frequency Histogram

You'll find more about probability density and relative frequency in this Knowledge Base article.

Q. Can I change the default, so that @RISK always shows histograms in relative frequency?

A. Absolutely! In Utilities » Application Settings » Simulation Graph Defaults, change Preferred Distribution Format to Relative Frequency.

Application Settings for Relative Frequency

Click OK, and answer Yes to the confirming prompt. This setting will affect all input and output histograms in all your models. Naturally, you can still use the histogram icon at the bottom of any graph to change the format of that graph.

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