Ideas for Managing at the Milestone

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Quantitative MethodsPart II

Ideas for Managing at the

Milestone

John C Goodpasture

Square Peg Consulting

www.sqpegconsulting.com

www.johngoodpasture.com

http://www.sqpegconsulting.com/

http://www.johngoodpasture.com/

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Milestones are hazards for on-time schedules!

• Milestones are dependent on everyone joining at the event—success for all depends on the successes of each

• Dependencies stretch things out—it’s a mathematical certainty

• Stretching at the milestone is called ‘merge bias’

• Merge bias explains the tendency for the schedule to ‘shift right’ at the milestone


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Milestones are dependent on everyone joining at the event

• Dependencies limit maneuver, limit agile responses, and take actionable options off the table

• Dependencies require effort to go into coordination—effort that costs money and takes away from other value-add work

• Milestone performance is dependent on the independent performance of each joining activity

– If any activity is late, the milestone is late– All the conditions for milestone success

must be jointly achieved

• If the milestone is on the critical path, then all the joining activities are near-critical

Photo: Dwight Tracy

Activity A1

Activity A2


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Dependencies stretch things out—it’s a mathematical certainty

• A milestone is the intersection of joining schedules

• Probability of making the milestone schedule is the probability that all joining schedules intersect on time

• The intersection is ‘stretched’ by the need to accommodate all the joining activities

• Consider 100 trials with 90% on time: – For 90 A1 opportunities on time, likely only 0.9 x 90

opportunities for A1 and A2 to be on time

– There are 9 + 9 + 1 opportunities to be late Photo: Neal McQ


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Example of schedule stretch

• When the intersecting activities are independent, then the probability of the intersection is the product of the intersecting probabilities

• Example: – A1 intersects milestone with 90% probability on-time, 10% probability of

being early or late, but adding similar A2 reduces performance• Probability of A1 and A2 intersecting—making the milestone on-time—is 90% x

90% = 81%• Probability of late = 90x10 + 10x90 + 10x10 = 19%

– Lower probability—81% vs 90%—translates to a likely longer schedule– Longer schedule is required to recover milestone probability to 90%

81%

100%90%

Intersecting activities stretch the opportunity to make the milestone

A1 or A2

A1 & A2

Time

MilestoneProbability


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Stretching at the milestone is called ‘merge bias’

• Merging activities create a bias toward ‘Shift right’ – To raise the probability from 81% back to 90%,

the milestone must ‘shift right’

• To counter the effects of merge bias:– Risk adjust all estimates with 3-point estimates

• Take risk adjustments into account when building the schedule

– Establish time buffers• Buffers are ‘reserves’• Size the buffer to cover the likely ‘stretch’

Photo ShiYali


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Read more about it!

• Quantitative Methods is a book about numbers and methods for applying them to practical situations in projects

• There is a good tutorial on statistics, accounting, balanced scorecard, and value

• The chapter on estimating is right out of my own experience

• The presentation on earned value makes EV really workable in day-to-day situations.

• If you do contracting, read the chapter on about doing risk management with contracts

• And, best of all, you can buy it at any on-line retailer, and read excerpts on google/books

http://www.jrosspub.com/Engine/Shopping/catalog.asp?store=&category=&itempage=&item=2996&itemonly=1


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I hope you liked what you saw here

• I hope you enjoyed this presentation. • You can share it with your network• There is a lot more information in the book, at

my company website, and at my BLOG. See the cover page for links

• By the way, there is information on my other books and magazine articles at sqpegconsulting.com

• You can contact me from my company website; the information is all there

https://www.linkedin.com/in/johngoodpasture

Ideas for Managing at the Milestone

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