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In Beta Distribution, (O 4M P)/6 . Why is M multiply with 4 and not any other number?

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Poonam Jain Project Manager| Morgan Stanley Hicksville, Ny, United States
Beta Distribution= (O+4M+P)/6

Here,
p= pessimistic
r= most likely
o= optimistic
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Stéphane Parent Self Employed / Semi-retired| Leader Maker Prince Edward Island, Canada
Oct 30, 2018 6:05 PM
Replying to Kiron Bondale
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Poonam -

Here's a possible answer - my eyes glazed over halfway through it but you might be braver than me: https://www.deepfriedbrainproject.com/2010/07/pert-formula.html

Kiron
You can skip to the very end of the article. The six sigma is the big clue that the weights for O, ML and P should add up to six.
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Stéphane Parent Self Employed / Semi-retired| Leader Maker Prince Edward Island, Canada
At the risk of being off topic, how many project managers have actually been given real values for most likely, rather than simply the hafl-way point between optimistic and pessimistic?
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1 reply by Wade Harshman
Sep 23, 2019 12:37 PM
Wade Harshman
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Stéphane, that made me laugh!

I've had better luck getting the "most likely" estimate first. Then we can talk about the ideal scenario in which everything is done early for our "optimistic" estimate. Then we can switch gears and talk about potential risks that could delay the work to get the "pessimistic" value (which can be kind of fun, if it doesn't get too unrealistic). And of course, these discussions can lead to changes in previous estimates, or changes to the risk register, etc.

Luckily I didn't need a super-formal method to get the initial estimates, just a project team talking to each other.
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Wade Harshman Scrum Master| GDIT Indianapolis, In, United States
Sep 23, 2019 12:17 PM
Replying to Stéphane Parent
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At the risk of being off topic, how many project managers have actually been given real values for most likely, rather than simply the hafl-way point between optimistic and pessimistic?
Stéphane, that made me laugh!

I've had better luck getting the "most likely" estimate first. Then we can talk about the ideal scenario in which everything is done early for our "optimistic" estimate. Then we can switch gears and talk about potential risks that could delay the work to get the "pessimistic" value (which can be kind of fun, if it doesn't get too unrealistic). And of course, these discussions can lead to changes in previous estimates, or changes to the risk register, etc.

Luckily I didn't need a super-formal method to get the initial estimates, just a project team talking to each other.
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Abolfazl Yousefi Darestani Manager, Quality and Continuous Improvement| Hörmann-TNR Industrial Doors Newmarket, Ontario, Canada
I agree with Sante!
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Latha Thamma reddi Sr Product and Portfolio Management (Automation Innovation)| DXC Technology Mckinney, Tx, United States
Math in PM great
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