11 December, 2023

Top-down and Bottom-up in Project Management: Which is Better?

By Mike Clayton

bottom-up, Reporting, top-down, WBS

In this article, we look at the relative merits of Top-down and Bottom-up. Let’s start by understanding what I mean by those terms.

Bottom-up: Detail First

When they think through a problem or a situation, some people have a clear natural tendency to start with the details. All the myriad little components come into their minds. Those who are naturally organized then sift and sort them into a pattern and a plan.

Top-Down: Start with Big Picture

Others approach a problem in a rather different way. They take the issue and steadily break it down into ever-smaller pieces until each component chunk feels like a manageable single concept.

Top-down and Bottom-up in Project Management: Which is Better?

Our Agenda

We will look at two contexts:

The Under-used Work Breakdown Structure

As project managers, we neglect our best tools at our peril and one of the very best is the Work Breakdown Structure, or WBS. Unfortunately, it seems to me that the WBS is chronically under-used and unloved. But never mind that, for now.

How can you develop a WBS?

The two natural approaches to problems reflect the two principal ways people approach developing a WBS:

  • Bottom-up
    We list all the tasks and then sort them into a structure.
  • Top-down
    We break the project into large logical chunks, and then keep subdividing them.

Important note: I am talking here about low criticality, ‘informal’ projects. For formal projects, the ‘correct’ way to develop a WBS is always top-down.

Natural Styles

Of course, most of us use a combination of both top-down and bottom-up planning. We also have a tendency to prefer one in some situations (familiarity, perhaps) and the other approach at other times. That’s fine.

The Best of Both Worlds

When asked, I always counsel that, by using both approaches, you will get the most thorough identification of all of your tasks. Indeed, I was recently asked by someone in an audience:

‘How can I make absolutely sure that I don’t miss a step?’

Absolutely sure… you can’t. But there are three ways to increase your confidence:

Work Collaboratively

When you involve lots of people, you get better ideas and make better decisions. But you have to do it right. In a marvelous book, The Wisdom of Crowds: Why the Many Are Smarter Than the Few, by James Surowiecki, we learn that one of the key criteria for success is diversity. So, involve as wide a spread of people as you can in brainstorming the tasks that need to get done.

Peer Review

Get other people to review your work. Tell them ‘I know I have missed something important and it’s bothering me because I can’t think what it is’. What this does psychologically is to activate the Pride Organ in their brains. You’ve asked them, and now that organ compels them to find the missing bits. You’ll be surprised what they come up with!

Do it Twice

If you are compelled to work alone on developing a list of activities, then there is still a way to benefit from both the top-down and bottom-up approaches. Here is a four-step process.

  1. Develop your WBS
    Do it in whichever style you would choose naturally – top-down or bottom-up.
  2. Put it in a draw safely for one or two days
    Just get on with something else for that time.
  3. Start again
    Develop a new WBS, without consulting your original work. This time, force yourself to do it in the other way (bottom-up or top-down) the one that does not feel natural.
  4. Compare your two pieces of work
    Look for the different approaches and extra ideas each one offers. Then combine them into a single, better WBS.

Some magic will happen here; two pieces of magic, in fact.

  1. First, doing the work a second time, but doing it in the non-intuitive way, will free up more creativity in your brain, to help you access new ideas and new ways of thinking. This combines fruitfully with the other piece of magic.
  2. Although you are not consciously thinking about the problem for two days, your unconscious mind knows you’re going to have another go. So, it will keep working on the problem, coming up with new ideas. Some will burst into our consciousness as ‘aha!’ moments. So, note down what you forgot. Others will simmer away until you free them with the second exercise.

The WBS ‘So what?’

Don’t neglect your WBS, do it with gusto, do it with friends and colleagues, do it twice – in two different ways.

Project Status Reporting: When Top-down and Bottom-up not Equally Effective

For informal projects, when you are creating a Work Breakdown Structure, top-down and bottom-up planning are equally effective. And I also believe that you can do better by combining the approaches and my blog describes how.

But Top-down and Bottom-up are not always equally effective.

In fact, in certain circumstances, one of them is a downright danger to the project manager.

How do you compile your project reports?

I am assuming you do compile project reports because, as much as most Project Managers hate report writing, we do understand its importance and value. Indeed, done well, reporting is a part of good monitoring and control, rather than the ‘distraction from real work’ that inexperienced Project Managers often tell me it is.

Once again, there are two approaches one could take: top-down and bottom-up.

Top-down Reporting

Figure out what your main message needs to be. Then, articulate it clearly and concisely. Supplement this with supporting evidence and relegate the detail and ‘mandatory’ data to an appendix. (I simplify a little)

Bottom-up reporting

Sift the evidence with care. Present it clearly, organized logically. Review what the data are telling you. From this, articulate the main messages. Summarize your main message in a clear and succinct statement. (more simplification)

These two caricatures reflect different ways people work

One of them, however, is fraught with danger. Which one?

Beware: Danger!

The answer lies in the field of human psychology. And it’s in an area of that discipline that project managers, change managers, and all professionals need to understand: decision-making. Whilst we are well equipped to make decisions in many circumstances, our in-built mechanisms can introduce dangerous biases at times; which lead us into deep and nasty traps.

The Most Dangerous Bias

One such bias, or trap, is called ‘the confirming evidence trap’. This biases us towards spotting evidence that confirms what we already believe to be true (regardless of whether the belief is correct). We selectively filter out dis-confirming evidence, or we acknowledge it and then interpret it incorrectly, to fit our existing belief.

Yes, if there is a mass of disconfirming evidence, we will eventually start to take note of it. But sometimes, one piece of contrary evidence can be a leading indicator of something important. Dismissing this can be easy to do, but disastrous.

Confirming Evidence Bias in Report Writing

The histories of ideas and of science are filled with examples, but let’s apply it back to our report writing. How does this bias affect our two approaches?

Whilst in both cases we are prone to bias, top-down reporting almost encourages it. It leaves you extremely unlikely to spot that one piece of data that you have already missed in your regular monitoring.

On the other hand, if you start your reporting process by gathering all of the evidence and reviewing it openly (ideally with a colleague or two), you are far more likely to spot the one piece of evidence that can lead you to a new assessment of your project’s status.

Job done! Your reporting has added real value, and if it only happens once in every dozen reporting cycles, it still justifies the time taken.

The ‘So what?’ of Project Reporting

Bottom-up reporting works. Top-down is quicker but more dangerous. Review your reporting procedures, and strengthen them to compile your reports bottom-up. Commit yourself and your processes to developing a deep understanding of your project status. And do so without prejudice or fear.

Learn More about Project Reporting

For more on Project Reporting:

What are your thoughts?

In particular, are there any other areas of Project Management where the Top-down or Bottom-up question is relevant? Do let me know in the comments below.

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Mike Clayton

About the Author...

Dr Mike Clayton is one of the most successful and in-demand project management trainers in the UK. He is author of 14 best-selling books, including four about project management. He is also a prolific blogger and contributor to ProjectManager.com and Project, the journal of the Association for Project Management. Between 1990 and 2002, Mike was a successful project manager, leading large project teams and delivering complex projects. In 2016, Mike launched OnlinePMCourses.
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