Point Lookout: a free weekly publication of Chaco Canyon Consulting
Volume 19, Issue 39;   September 25, 2019: Planning Disappointments

Planning Disappointments


When we plan projects, we make estimates of total costs and expected delivery dates. Often these estimates are so wrong — in the wrong direction — that we might as well be planning disappointments. Why is this?
The Leonard P. Zakim Bunker Hill Bridge

One of the many problems contributing to cost overruns in the highway project known as Boston's "Big Dig" was a sequence of delays in determining the design of the Charles River Crossing. Once this decision making overran its schedule, very serious problems developed later in the project, in both management and engineering and construction. As in the private sector, the early focus of scrutiny has been on the engineering and construction rather than on management, in part because we measure them more carefully. Pictured is the Leonard P. Zakim Bunker Hill Bridge in a later construction phase, as it emerges from the Thomas P. "Tip" O'Neill Jr. Tunnel to cross the Charles River. This particular crossing is very near the one referred to as "two if by sea," in the poem, "The Midnight Ride of Paul Revere", by Longfellow (1860). Photo courtesy Massachusetts Turnpike Authority.

When people estimate how long a piece of work will take — or how much it will cost — their estimates are fairly reliable if they've done lots of similar work before. But if the work is unfamiliar, or if there are significant unknowns associated with the work, estimates of cost and schedule tend to be far less accurate, even when all we asked for was a "rough estimate." And the inaccuracies are almost always of a certain kind: final costs tend to exceed estimates, and deliveries are often late.

Why does this happen?

Last time, I explored three important contributors to this pattern — the planning fallacy, self-serving bias, and organizational politics. But in addition to these sources of systematic errors, there are two conceptual errors that are a bit mathematical in nature. One is a general misunderstanding of the term "rough estimate," and the second is a misconception about the shape of probability distributions of costs and schedules for unfamiliar projects.

Misunderstanding the term "rough estimate"
Rough estimates can be useful if we understand the true meaning of "rough." Technically, a rough estimate is an estimate that has a relatively wide margin of error. Every estimated value has a band of values that corresponds to, say, 95% confidence, and a mean or average that corresponds to a point within that band. If the width of the 95% confidence band is W, and the mean is M, then there is a ratio R equal to W/M. The "rougher" the estimate is, the greater is R.
To be safe, users of rough estimates need to use the value at the top end of the band for estimated values in which larger is worse, or the value at the low end of the band for estimated values in which smaller is worse. Too often, people just use M. They can be forgiven, of course, when the estimator provides M alone, without reference to a 95% confidence band.
There are clear reasons for this. In my experience, many consumers of estimates — the decision makers, as they're often called — are uncomfortable with any estimate that includes an uncertainty band. I've actually heard reports about decision makers' responses to estimates of the form, say, 8.7 million +/- 1.5 million, that go like this: "Don't give me this +/- stuff! If you don't know how much it will cost, just admit it! Now give me an estimate! Exactly what will this cost?"
In fairness, Rough estimates can be useful
if we understand the true
meaning of "rough"
many estimators lack sufficient information needed to compute a 95% confidence band. Others aren't sure how to calculate it. Others are intimidated by decision makers who reject the "+/- stuff," and still others aren't intimidated, but just don't want to fight with resistant decision makers. Whatever the case, estimates without 95% confidence bands are common, and because the estimates lack these bands, overruns are defined as "less favorable than the so-called estimate," which makes overruns very likely.
The shape of probability distributions of costs and schedules
Another source of estimation error is our human intuition about the shape of the probability distributions of costs and schedules. We tend to think of these distributions as fairly symmetrical around some average, or mean. And we also like to believe that the mean of, say, the cost distribution, is fairly close to the most likely value of that distribution.
We base this intuition on our experience with familiar efforts. And as it happens, for familiar efforts, our experience is a useful guide. That is, the distribution of cost or schedule outcomes for familiar efforts is fairly symmetric around some average value.
But for unfamiliar efforts, our intuition is misleading — sometimes grossly misleading. And this comes about for reasons that are easy to understand intellectually, but difficult to incorporate into our intuition.
With unfamiliar efforts, or efforts that are subject to significant unknowns, the probability distributions for costs and schedules aren't symmetric about their means. In fact, they're wildly asymmetric. While there are some pretty hard limits on how quickly or cheaply things can happen, there are no analogous limits on how slowly or expensively things can happen. For example, no matter how hard you try, you probably cannot get to the conference room in the other building in less than 45 seconds — even if you run. But without trying to dawdle, it can sometimes take you 20 minutes to get there, even though it's only a five-minute walk, depending on the weather, who you run into on the way over, and whether or not you have to go back to pick up something you forgot.
For unfamiliar projects, or projects subject to significant unknowns, the probability distributions for costs and schedules tend to have long "tails" corresponding to unanticipated costs and delays. These tails cause the distributions to have average values that can be much greater than their most likely values. And that's what throws off our intuitions. When we estimate, we tend to estimate the most likely value. And when the average value is much greater than the most likely value, our estimates tend to fall crazily short. The situation is even worse when we stack one task or project after another in a long train, because the uncertainty bands stack up.

Next time you make or receive an estimate without a 95% confidence band, ask yourself, "What are the lowest and highest values that wouldn't shock me totally senseless beyond all reason?" That should give you some idea of what 95% confidence means. Go to top Top  Next issue: Start Anywhere  Next Issue

How to Spot a Troubled Project Before the Trouble StartsProjects never go quite as planned. We expect that, but we don't expect disaster. How can we get better at spotting disaster when there's still time to prevent it? How to Spot a Troubled Project Before the Trouble Starts is filled with tips for executives, senior managers, managers of project managers, and sponsors of projects in project-oriented organizations. It helps readers learn the subtle cues that indicate that a project is at risk for wreckage in time to do something about it. It's an ebook, but it's about 15% larger than "Who Moved My Cheese?" Just . Order Now! .

Your comments are welcome

Would you like to see your comments posted here? rbrenHoWzUJVeioCfozEIner@ChacbnsTPttsdDaRAswloCanyon.comSend me your comments by email, or by Web form.

About Point Lookout

Thank you for reading this article. I hope you enjoyed it and found it useful, and that you'll consider recommending it to a friend.

Point Lookout is a free weekly email newsletter. Browse the archive of past issues. Subscribe for free.

Support Point Lookout by joining the Friends of Point Lookout, as an individual or as an organization.

Do you face a complex interpersonal situation? Send it in, anonymously if you like, and I'll give you my two cents.

Related articles

More articles on Project Management:

Two colleagues chatting on their morning breakNine Project Management Fallacies: I
Most of what we know about managing projects is useful and effective, but some of what we "know" just isn't so. Identifying the fallacies of project management reduces risk and enhances your ability to complete projects successfully.
FlamesHow to Get Out of Firefighting Mode: II
We know we're in firefighting mode when a new urgent problem disrupts our work on another urgent problem, and the new problem makes it impossible to use the solution we thought we had for some third problem we were also working on. Here's Part II of a set of suggestions for getting out of firefighting mode.
Selling an ideaRisk Creep: II
When risk events occur, and they're of a kind we never considered before, it's possible that we've somehow invited those risks without realizing we have. This is one way for risk to creep into our efforts. Here's Part II of an exploration of risk creep.
A scientifically accurate atomic model of the external structure of the SARS-CoV-2Vendor Mismanagement
When we outsource knowledge work to vendors, we expect to achieve the desired result with less risk and uncertainty than if we did the work ourselves. But mission creep, mission retrenchment and employee capture can lead to less welcome results.
The side mirror view from an automobilePremortems
Premortems are simulated retrospective examinations of future events, conducted as if those future events had already occurred. By combining the benefits of psychological safety with a shift in temporal perspective, they offer advantages for planners.

See also Project Management and Personal, Team, and Organizational Effectiveness for more related articles.

Forthcoming issues of Point Lookout

A wolf pack, probably preparing for a huntComing June 14: Pseudo-Collaborations
Most workplace collaborations produce results of value. But some collaborations — pseudo-collaborations — are inherently incapable of producing value, due to performance management systems, or lack of authority, or lack of access to information. Available here and by RSS on June 14.
A meeting of a small team working to resolve a serious matterAnd on June 21: Asking Burning Questions
When we suddenly realize that an important question needs answering, directly asking that question in a meeting might not be an effective way to focus the attention of the group. There are risks. Fortunately, there are also ways to manage those risks. Available here and by RSS on June 21.

Coaching services

I offer email and telephone coaching at both corporate and individual rates. Contact Rick for details at rbrenHoWzUJVeioCfozEIner@ChacbnsTPttsdDaRAswloCanyon.com or (650) 787-6475, or toll-free in the continental US at (866) 378-5470.

Get the ebook!

Past issues of Point Lookout are available in six ebooks:

Reprinting this article

Are you a writer, editor or publisher on deadline? Are you looking for an article that will get people talking and get compliments flying your way? You can have 500-1000 words in your inbox in one hour. License any article from this Web site. More info

Follow Rick

Send email or subscribe to one of my newsletters Follow me at LinkedIn Follow me at Twitter, or share a tweet Subscribe to RSS feeds Subscribe to RSS feeds
The message of Point Lookout is unique. Help get the message out. Please donate to help keep Point Lookout available for free to everyone.
Technical Debt for Policymakers BlogMy blog, Technical Debt for Policymakers, offers resources, insights, and conversations of interest to policymakers who are concerned with managing technical debt within their organizations. Get the millstone of technical debt off the neck of your organization!
Go For It: Sometimes It's Easier If You RunBad boss, long commute, troubling ethical questions, hateful colleague? Learn what we can do when we love the work but not the job.
303 Tips for Virtual and Global TeamsLearn how to make your virtual global team sing.
101 Tips for Managing ChangeAre you managing a change effort that faces rampant cynicism, passive non-cooperation, or maybe even outright revolt?
101 Tips for Effective MeetingsLearn how to make meetings more productive — and more rare.
Exchange your "personal trade secrets" — the tips, tricks and techniques that make you an ace — with other aces, anonymously. Visit the Library of Personal Trade Secrets.
If your teams don't yet consistently achieve state-of-the-art teamwork, check out this catalog. Help is just a few clicks/taps away!
Ebooks, booklets and tip books on project management, conflict, writing email, effective meetings and more.