This topic really gets Wes going. He was traveling to Wikipedia articles left, right, up, and down when he tried to explain this one to me. A few of those articles are included here so you too can get a taste of the "Wes Experience" when he gets going on a topic he's passionate about. Please enjoy the humorous display of over-exaggerated hyperbole:
Yes. It's true. Project Insight carries its calculations on duration and hour values many more decimal places than MS Project. This can cause differences in calculations when summarizing/totaling many values because on the front end you see rounded numbers, but the backend is calculating to more detail.
For example, 33 percent of one eight hour work day equals 2.63 work hours. Project Insight will calculate the entire number. 100 tasks with this value will come out to 263.33 hours in PI. MS Project will take those same 100 tasks and calculate them for a rounded total of 264 hours.
Not proper rounding? We agree. This quirkiness is more common than you might think because day and time calculations are more like the English system of measurements and not like the metric system.
We don't like it either.
Leave me a comment if I'm on the right track...