Low and high duration in Microsoft Project

November 20, 2015

Q: Low and high duration in Microsoft Project
Hi, we are evaluating RiskyProject and it seems that even though I changed estimates for low and high, it still seems to be calculating with previous numbers.

A: When you are using the RiskyProject Addin to run schedule risks analysis, there are a few key things to be aware of. You must identify the field that you will be using for the Low and High estimates in the Field Mapping. By default it is Text11, but can be any text field that is available. Once this is mapped, you should not change this setting as this is where the Addin looks to apply statistical distribution during the Monte Carlo simulation.
When you are first adding the low and high estimates, you must provide a statistical distribution by using the Input Distribution > Duration dialog box.
Once this is done, you can modify the Low and High estimates without using the dialog box. However , this will bypass any error checks that are done when you input the data, for example you cannot enter a low estimate that is greater than the base duration. Looking at your file, I found a few things that could be causing the issues you are seeing. If you are modifying the data without using Duration dialog box, it is possible to enter values in which Low > Base or High < Base or Low which could cause errors.
If you look at the image below, I have indicated a few issues in the data that should be addressed.

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