As a project manager or as project team member, you need to make more than one estimate during the project.

- How long will it take to complete ?
- How much will it cost to realise ?
- etc

Those who make the decision need to make sure their estimations are as accurate as possible, so how can you reflect "certainty" or "uncertainty" in your estimates?

I recently discovered an interesting tool developed by William W. Davis, MSPM, PMP, the Project Management Superhero , to get this done easily !

#### Estimating or guessing ? That's the question.

Making an estimate might look like guess work, but when you have your facts and figures under control it will become a well calculated estimate instead of a "guesstimate".

William W. Davis has bundled his expertise into a Microsoft Excel sheet or workbook. He combines the classic 3-point PERT (*Project Evaluation and Review Technique*) with some statistical mathematics.

#### Classic 3-point estimate

The classic PERT uses three values to calculate the estimate value :

- minimum (MI),
- most likely (ML),
- maximum (MA)

The estimate value is then calculated as : (MI + 4xML + MA) / 6

This is pure mathematical and thus not reflect any certainty or uncertainty about the 3 base values MI, ML, MA.

#### The SPERT method developed by William

The additional "S" does not come from *SuperHero* or *SuperPower*, but it relates to **Statistics** and **Sensing**.

Statistical PERT is a five-step process (but a SPERT template makes it only three steps). The five steps are:

- Identify a minimum, most likely and maximum outcome for some uncertainty
- Calculate the expected value using the PERT formula
- Make a subjective judgment about
*how likely*the most likely outcome really is - Calculate a standard deviation
- Choose any probabilistic estimate that fits your desired risk level

SPERT templates do steps 2 and 4 for you, and Excel’s statistical functions in Step 5 make that a snap.

#### FREE !

William offers all Statistical PERT example workbooks and templates, for free, to everyone.

**free SPERT template**.

He wants to remove barriers that keep people from exploring their own statistical superpowers, and he wants to encourage all businesspeople – especially project managers – to use statistics to quickly align stakeholder expectations and improve executive decision-making.

Go get it now !