TOPIC: Ranges for estimates in PM Formulas Guide

Hello!

I bought a PM Formulas Study guide along with PM PrepCast.
In this guide there are ranges for estimate such as: rough order of magnitude (ROM), preliminary, budget, definitive.
I`ve found in PMBoK ranges for ROM and definitive estimates.

But where ranges for preliminary, budget and final estimates came from?

Dmitry,

Please see page 9 of the PM Formula Study Guide, where we have the following explanation at the bottom of the page:

The Estimate Ranges Disagreement
We often receive questions from students about the fact that they see different numbers for the “Estimate Ranges” when they compare various training materials. That is true, because there is unfortunately no final authority that defines these ranges.

There is disagreement both on the names as well as on the actual ranges. Some books set the ROM at -25% to +75% others at -50% to +100%. This is not surprising because estimate ranges are both application area and industry dependent. Everyone does it slightly differently in their industry and on their projects. So it really isn't surprising that you will see different numbers in different books.

The numbers that we provide in the table above have been successfully used by our students on the exam, so we believe them to be a good approach for the exam.