The difference between Complex and Complicated Projects

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Paul Naybour
Paul is a project management consultant and account manager with particular expertise in the analysis, process development, and implementation of change program management, risk management, earned value management, and bespoke project management training development and delivery. Paul is the Business Development Director of the company Parallel Project Training

What is meant by a complex project?

The world is full of different opinions about what we mean when we talk about complex projects. Is complexity the same as complicated? By complex do we just mean a large project, one which is geographically distributed or using complex technology? Or are these mega projects, in fact, just more complicated.


In Earls’ book Herd: How to Change Mass Behaviour by Harnessing Our True Nature, specifically, his definition of the difference between complex and complicated is:

A jumbo jet is complicated; mayonnaise is complex.


By this I mean, a jumbo jet is made up of millions of tiny parts. If you only had the time, the patience, the skill and a good manual, you could take the plane apart and eventually put it back together again.

Mayonnaise is different: it is a stabilized suspension – the result of the interaction of its ingredients… and the way you add them to each other. You can’t take mayonnaise apart to produce the original ingredients and then recombine them, as any amateur cook knows. So complicated is reducible and recombine-able; mayonnaise, on th eother hand, is neither of these things.

Here is an important lesson: mass behavior is inherently complex because it is based on the interaction of individual agents. But we try to understand it as if it were complicated… This is why we find it difficult to understand.

I think complexity is closely related to the ambiguity of project goals and the method of delivery, because complexity is caused by the challenges of planning the project in the first place and likely level of anticipated change. This complexity makes it impossible to sit down and plan the project in a clear way from start to end; we need a slightly more flexible approach to the traditional “plan the work” “work the plan”. This can be represented by an adaptation of Rodney Turners classic goal method matrix

The higher the levels of ambiguity about the project goal and uncertainty about the delivery method make it more difficult to manage in a traditional way. This seems more important than the pure size of the project. Some large complicated projects have clear goals and known methods and these can be managed in a very traditional way.

Take, for instance, a digital marketing campaign for a well-funded startup business. There may be many different aspects to it following the design & development of a new website: there could be paid advertising, social media marketing, content marketing, search engine optimisation, conversion rate optimisation. However, all of these elements are striving to deliver the same goal: good rankings, visits, sales so there is no ambibuity about the project goal and fundamentally little  uncertainty about the delivery method. This makes a digital marketing campaign inherently complicated but not complex.


The definitions here of complex or complicated differ from the normal multi organisation; multi-phase definition defined by the APM, but is nevertheless more relevant to help think about the complexity of the projects we manage.


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