Reverse Engineering the Work Formula in Microsoft Project

At the heart of planning a project using Microsoft Project is the daunting responsibility of assigning Resources to Tasks. Worse still, try adjusting those assignments (both during planning and monitoring) and see what happens.

A confusing facility in Microsoft Project is the way Duration, Units of Resources and Work Loads per Task are interact with one another.

The Work Formula is clear: Work = Units x Duration. But there are 2 major options that make Microsoft Project behave in diverse ways, some of them unintuitive. One is a field called the Task Type (Fixed Work, Unit or Duration) and the other is a field that defines whether a Task is Effort Driven or not.

Try as I might, I could not get books, blogs or training material that carried the Work Formula logic to the end.

The time was ripe for Reverse Engineering. We have a black box called Microsoft Project and its Work Formula is programmed to work in ways more mysterious than a Project Manager’s mind. The box has a lot of input and a fewer outputs. Which inputs do we use to which output?

To Reverse Engineer the Work Formula, we will:

1. Analyze the two Task fields (columns): Task Type and Effort Driven
2. Identify all possible combinations of input (scenarios)
3. Try each one to see how Microsoft Project behaves (output)
4. Arrive at a decision logic that allows us to know where to use which setting.

The discussion is length and has been detailed in a PDF white paper.

The white paper is accompanined by Microsoft Project and Excel files which are found in a zipped file

I would be very interested in your comments through this post.