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The Stacey Matrix

The Stacey Matrix is a crucial tool in the realm of project management that was invented in the 1990s from Ralph Douglas Stacey. Stacey, a researcher in the field of complexity and management theory, wanted to find out what factors influence complexity. It gained prominence primarily through Ken Schwaber, one of the co-founders of Scrum in the early 2000s.

What is The Stacey Matrix?

The Stacey Matrix is a tool for representing and managing complexity in projects. It consists of two axes: Requirements (y-axis) and Approach (x-axis). Requirements represent “what” needs to be developed, while the Approach represents the 'how'.


The Stacey Matrix


It is commonly used in software development and IT consulting to determine the complexity of a project or task

Within the axes, there are four areas:

  1. Simple
  2. Complicated
  3. Complex
  4. Chaotic

The character of a project is determined along the bisecting line. The closer the prerequisites are to the intersection of the axes, the simpler it is. The project has a clear goal and there is a traditional, known approach. As one moves further away from the intersection, one first encounters complicated and complex areas, before reaching the area where both the requirements are unclear and ambiguous and both the actual goal and the approaches are completely unknown. In the IT sector, this case is often referred to as "agile" and an agile framework is relied upon for problem-solving.


The zones of the Stacey matrix


Four Examples of Classification Into Individual Project Types

The structure of the Stacey Matrix becomes clearer when we illustrate the four areas of the individual project types using examples.

Simple Projects

A simple project is one where both the requirements and the approach are known. For instance, one can develop a system using a technology that all participants are already familiar with to meet requirements that have been met many times before. In such cases, one speaks of "simple" or "trivial" projects, where the solution is clear and unequivocal. Here, the classic waterfall model is suitable as a project management method, as only the known steps in a project need to be worked through.

Complicated Projects

However, if one or both of the initial factors change, one first speaks of complicated projects. For instance, in IT, a new technology is being used that is not yet fully mastered, or new requirements must be met that have never before been implemented by the team. In such cases, more time needs to be invested in preliminary work, as one is moving on less familiar terrain. Examples include using a new JavaScript library in development, entering a new market, or introducing a new invoicing tool.

Chaotic Projects

It goes even further when both the solution approach (or technology) and the requirements are completely unknown - an area called "chaotic". The question arises, how does one plan a project when neither the requirements nor the approaches to be used are partly unknown? The answer is simple: one can't. Chaos can't be planned.

This is also the reason why, especially in IT, agile frameworks like Scrum or Kanban are used in this case. When neither the requirements nor the approaches are known, one must gradually approach the supposed goal.

The current most famous examples of Chaotic problems in consulting are the economic crisis, a pandemic like COVID-19, or wars.

Complex Projects

However, between the complicated and the chaotic area lies another fascinating area called "complex". In a complex system or project, the boundary conditions - requirements and approaches - can be set and left unchanged so that the system can self-organise within these boundaries.

A consulting example for this is the development of a new business model or the introduction of a new product.

The Problem Statement in the Case Interview

The Stacey Matrix serves as a decision-making tool and can help to identify a case or a problem. After all, the solution approach and familiarity with the methods provide the basis for the implementation strategy and thus the case type.

By using the Stacey Matrix for the case at hand or the respective project, clarity is created for the upcoming tasks. By first determining the 'What' requirements on the Y-axis and then defining the 'How' on the X-axis, the solution path and implementation can be derived.

Advantages and Disadvantages of Using The Stacey Matrix in Consulting

The use of the Stacey Matrix in consulting primarily serves to visualise the problem at hand. This results in advantages and disadvantages of using it in a case interview, with the client or within projects:


  • The Stacey Matrix is quickly drawn by hand and can be used on either a flip chart or a piece of paper to explain the situation to the stakeholders.
  • All stakeholders can evaluate a project before it starts and thus recognise potential frustration early on.
  • Challenges, as well as responsibilities, can be revealed early on to influence, for example, personnel decisions.
  • The division into 'What' and 'How' allows for a clear structuring of the argumentation and approach.


  • In practice, the 'What' is usually determined by higher management and not the 'How'. This can make it difficult to make a complete classification.
  • The Matrix provides no hints or approaches to the existing problem. Moreover, depending on the level of experience, participants can assess a project very differently.
  • It is a model. Real conditions such as the project environment, the available resources and time are not taken into account.
  • Depending on its use, the Stacey Matrix can be instrumentalised for one's own purposes and not adjust the approach to the project, but adjust the project to the approach.

Conclusion on the Stacey Matrix

Especially in agile or digital transformation projects, the Stacey Matrix is a frequently used tool to determine the complexity of corporate structures, processes, and projects. Especially in the area of decision-making in complex or chaotic situations, it can help to find a suitable project management approach as quickly as possible.

Depending on experience, however, one should be careful that the actual purpose of the Matrix is not subordinated to one's own interests, for example, to select a specific, familiar solution approach (Waterfall, Lean, Agile).

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