Voices on Project Management

> Back to Voices Home

Unrealistic Detail Only Sets You Up for Failure

| | Comments (3) | TrackBacks (0)
It's impossible to accurately predict the future. Yet, many project managers continue to try. They create schedules that implicitly state a task will be completed at 3:30 on a Tuesday afternoon, in four months. Or they predict that the total cost of their project will be precisely $10,986,547.55.

Yet these pseudo-accurate estimates based on detailed calculations are no more accurate than estimates made in more general terms and covered with an appropriate range indicator. Achieving a detailed estimate for an $11 million-plus project to within -5 percent to +10 percent indicates a very careful estimating process in a stable, well-understood environment.

Attaching a precise number calculated to the nearest cent only raises stakeholder expectations about the degree of accuracy possible. And that leads to perceived "failure" when the stakeholder's unrealistic expectations are not realized.

Similar problems arise if a project is scheduled in hours, and the work extends for more than a few days. Planning a project over several months on an hourly basis produces a mass of inaccurate data once you get beyond the first few days. And again, when the project fails to achieve the degree of control over the future implied by the excessively detailed schedule, it will seem like it failed.

Pragmatic estimating at an appropriate level of detail sets realistic expectations. But beware: Your stakeholders may already have unrealistic expectations of what is possible from previous projects that "failed."

Dealing with this issue requires skills in managing upward -- a topic for a future post.


Bookmark and Share


The views expressed within the PMI Voices on Project Management blog are contributed from external sources and do not necessarily reflect the views and opinions of PMI.

0 TrackBacks

Listed below are links to blogs that reference this entry: Unrealistic Detail Only Sets You Up for Failure.

TrackBack URL for this entry: http://blogs.pmi.org/mt-tb.cgi/641

Leave a comment

All comments are reviewed by our moderators, and will not appear on this blog unless they have been approved. Comments that do not relate directly to the blog entry's contents, are commercial in nature, contain objectionable or inappropriate material, or otherwise violate our User Agreement or Privacy Policy, will not be approved. For general inquiries not related to this blog, please contact Customer Service. Please read the Comments -- Question and Answers.


Estimating can be a complex process but it has to be done to be able to assess the feasibility, relevance and benefit of doing the project. It also serves as a good target for the team.

We must remember though that it also has to evolve as the project progresses as more previously unknown factors start to reveal themselves.

An estimate must always contain "the error band" that Lynda described and the band preferably reduces as the project moves forward. A project can thus start to have a band of say 90-95% confidence at the very early stages of formation, depending on the perceived risks,unknowns, assumptions and experience of the team and as the project progresses - the confidence level can preferably improve although in some situations it can actually go down when a previously unknown derailer derails a project.

This is the reason as well why we estimate the project cost (with the confidence level) along with an estimate for contingencies to ensure that if a risk becomes an issue, the project itself can still survive IF it still makes sense at that point time to actually have it survive and an estimate at that point helps this decision as well.

Can we predict the future? We could and should but always accompany that prediction with a confidence level at least.

Think "weatherman" and his prediction would be like "There is a 30% chance of rain this coming Saturday". Will it rain on Saturday? Maybe but then again he just said 30% chance. Same with project estimates.

Good post, Lynda.

It is not only detail that can be unrealistic in schedules though. I have had the chance to take part in volunteer events planned by other project managers.

The thing is that start time of these events was during my working hours or it was the hour I am supposed to leave the office so I had no chance to be at these events on time. It was the same for other participants. Isn't it better to keep in touch with reality when we plan?


Actually the statement "it is impossible to accurately predict the future," is false.

The falsehood comes because the confidence intervals and the error band on the prediction are missing.

The future is predicted all the time. Including project managers. We can predict with high confidence the expenditures for the month of October on our $800M flight avionics contract. The launch management staff (USAF) can predict quite accurately the liftoff time of an Atlas V Heavy with an NRO payload on board to the week of the month. The exact minute of departure has a error band and a confidence. And most critically important that minute of launch has a "protection buffer" for both the launch time and the on-orbit processes to make up for anything that is late.

What is missing from the discussion, and a critical point rarely discussed is that all project activities are random variables.
The prediction using these random variables have simple (high school) statistics around them.

So it is not technically correct to say "It's impossible to accurately predict the future." It is correct to say, "..., many project managers continue to try. They create schedules that implicitly state a task will be completed at 3:30 on a Tuesday afternoon, in four months. Or they predict that the total cost of their project will be precisely $10,986,547.55."

But these projects managers are ignoring the underlying statistical processes of projects and in fact nearly everything on earth. Even our atomic clock here in boulder has a confidence level and an error band on that confidence for time marks in the femto-second range.

The real problem is the failure to acknowledge the variances. The second problems is the over generalization of a statement like "it is impossible to predict the future."

In fact I'm going to make a prediction of the future now. I predict that with a 99.8% confidence and a 0.01% error that when I press the submit button, this post will do just that post.

See I'm a Program Manager and I predicted the future.

About This Blog

Voices on Project Management offers insights, tips, advice and personal stories from project managers in different regions and industries. The goal is to get you thinking, and spark a discussion. So, if you read something that you agree with — or even disagree with — leave a comment.

All posts represent the opinions of the bloggers.

Follow PMvoices on Twitter

About Bloggers

Keep checking back because the voices for this blog will continue to grow and change to represent a variety of regions, industries and opinions.

Read blogger profiles

Voices Poll