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Project Managers are expected to guess the future, a difficult task even in sciences like meteorology. As many projects finish late (due to expanded scope, underestimated durations, etc), it is tempting to pad estimates.

When is it okay (or not okay) to do so? Off the top of my head, it is risky to share padded estimates with project team members (as they will expand their work to fit the expanded timelines), and risky to share padded estimates with management (as they will add some padding of their own before passing the schedule upwards). On the other hand, planning a schedule with no padding is pretty much guaranteed to lead to a late project.

Thoughts?

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You should always work with a range of estimates: Most likely and worst case. Add margins at the risk spots in your schedule and at the end, but make them clear for all to see. That is the professional way of managing projects.

Manage your team members against the most likely estimates. They'll have no issue working on the edge when they know that there is room to manouvre when Murphy strikes.

When you have your contingencies worked out well, management will have no reason for padding.

In my experience, transparancy works best.

  • Well said. +1 for the estimate range. No such thing as a single-point estimate. – David Espina Apr 1 '11 at 11:18
  • +1 for range of estimates. There are great details about it in O'Reilly's Applied software Project Management, chapter III: Estimation. projektura.org/usp/… – Tiago Cardoso Apr 1 '11 at 12:45
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It is never okay to pad. Contingencies are calculated and added to the PMB to handle uncertainties in your time and cost estimates.

  • PMB = Project Management Baseline? – Sean Earp Mar 31 '11 at 21:29
  • I'd say that contingencies are added to project budget. See my answer to this question: pm.stackexchange.com/questions/943/… – yegor256 Apr 1 '11 at 8:21
  • Contingencies can be both time and budget. You can add margins in your schedule; see Stephan's response below. – David Espina Apr 1 '11 at 10:48
  • Yes, PMB is project management baseline. – David Espina Apr 1 '11 at 10:49
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It's better to under-promise and over-deliver than it is to over-promise and under-deliver. Padding your estimates by adding a safety buffer will help ensure you're in the first category and not the last category.

It's impossible to predict the future, especially if you're estimating something that contains many tasks you don't have experience with.

  • 1
    Beware of Parkinson's Law and Student Syndrome. Adding padding rarely delivers the under-promise, over-deliver notion but will most always increase costs. – David Espina Apr 1 '11 at 11:23
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'Padding and Estimate' is a skill and a base requirement for a PM - it's actually Risk Management, right? A plan is an map of where you are going and how long it will take to get there, neither are certain because neither have happened yet. You need to 'pad' or accommodate for a change in direction and a change to work effort based on events that have not happened yet (such as a change in developers, new technology, internal/external business changes/influences). A good approach is to compare prior projects for the same company/team and see how their original estimates matched up against the final. Another good approach is to develop a risk grid that includes a potential of occurrence and impact potential - with a range of time/$'s - you can use that as a 'risk pad' for the project.

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