A new project triangle: Time, Cost and 5-Dimensional Product

The project triangle addresses the premise that a project has three dimensions, at least one of which must have some flexibility. It is, effectively, a pre-requisite for high-level prioritisation and release planning. Nearly all depictions of the project triangle have Time and Cost as two of the corners. There’s less consistency when it comes to what the third corner is all about. I think there’s a good reason for this: the third corner is complicated. Just as the project triangle is about considering and confirming the business’ tolerance for movement across the three dimensions, I think the third corner is also made up of several dimensions, each of which needs to have been considered before we can make informed decisions about prioritisation throughout the rest of the product development lifecycle.

The third corner is sometimes known as “scope” and sometimes known as “quality”.

Whether we go for “Scope” or “Quality”, either is unsatisfactory, as neither term adequately conveys the complexity of that third corner – and because the words “Scope” and “Quality” mean different things to different people (which has greater quality, a chain of steel or string of pearls?).

The “project tetrahedron” tries to accommodate both “Scope” and “Quality”. This is also unsatisfactory, primarily because “Scope” and “Quality” are simplistic and again ambiguous terms.

In practice what we’re trying to find is the right balance between Cost, Time, and a bunch of other things more complex than just “scope” and/or “quality”, that taken together define what product or outcome is desired. So the third corner of the planning triangle should be known not as “Scope” or as “Quality” but as “Product”.

Now, if we know from the outset exactly what the product/outcome needs to be, then a simple triangle would suffice, the Product corner would be fixed and Time and Cost would need to be flexible. But in practice we usually can’t guarantee at the outset exactly what the product needs to be.

What we can know is the business’ tolerance for change or flexibility that can be applied to each of the dimensions that comprise the product.

I propose there are probably five useful, manageable dimensions to product:

• Scope This is what’s within our remit and, usually much more usefully, what is not within our remit. “Scope” is usually applied to business requirements, objectives, success criteria, etc rather than directly to the products. “Scope” is the boundary within which we expect the product(s) to exist, regardless of the quality or detail of the delivered products.
• Feature set is the large-grain components that collectively are expected to make up the product.
• Bells & whistles are the finer-grained, more discretionary components; they might make things more fun, or accommodate more scenarios, or provide more options.
• Gold plating is the discretionary side of quality, the nice, unnecessary, welcome and often brand-based touches.
• Performance is the other (less discretionary) side of quality: the standards that must be met, the weight/pressure/volumes that must be borne, the capacity that must be delivered.

Once we look at our product as a combination of these five dimensions it becomes easier to see how the “product” corner of the triangle can have flexibility just as Time and Cost can have flexibility. In the context of the planning triangle, statements like “Scope is fixed” or “Quality can’t be compromised” are too simplistic.

Thinking in terms of a product corner made of several dimensions also sets a framework for future ongoing prioritisation. When we write users stories and plan sprints we are thinking through these product dimensions (whether or not we explicitly acknowledge them as such). I’m sure the developers and the business can work together more effectively if these dimensions are clearly articulated, particularly at the early stages.

Thinking in terms of a product corner made of several dimensions also makes a significant contribution to defining the criteria to be met by a first live release.

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