A simple explanation of the time/cost/quality triangle and why it matters

Lab Blog Article

  • Published — Nov 2019
  • Topic — Quality Assurance
  • Author — Simon Conway

How does the project triangle work?

The project management triangle is a simple way to understand the relationship between time, cost and quality. Usually, you’ll find one or two of these constraints are fixed and the other one or two are therefore variable. Please explain? Ok…

If your time is non-negotiable, the quality of your deliverable will depend on the resources you have available.

If the quality can’t be tinkered with, the cost of your project will be down to how much time you can add.

In some situations, you’ll find that two sides of the project management triangle are locked down. This scenario can make things a little tricky, but it’s really common.

Want it on time and cheap? Your quality or functionality will suffer. Aiming for cheap and great quality? This will take longer. Delivering on time and great quality? This will be more expensive to deliver.

The time constraint

This is simply the amount of time it takes to complete your project or program. And for many stakeholders, the deadline is their only focus — it’s how they’ll judge the success of the project.

In this case, your options are to add more resources to meet the deadline, which will add to the cost. Or you can look at reducing the quality of the outcome.

The cost constraint

More than just the financial cost, this is all the resources needed to deliver the project. It can include machinery, software, labour etc.

Cost is undoubtedly a critical consideration in many projects. So if you’re working within a fixed budget, you can adjust the project deadlines. Or make cuts to the quality of some or all of your deliverables.

The quality constraint

This refers to the quality of the products and services the project is delivering. What’s are you delivering, how good it is, and how much of it. Is the deliverable fit for purpose?

Your client might want to add features during the project to meet their personal fit for purpose objective. So if quality is number one, your stakeholders will need to be flexible on the time it takes to deliver the outcome. Or accept an increase in the cost.

Often you’re left with no choice but to cut functionality out. This doesn’t mean losing core requirements – you can’t touch those. But additional functionality can go into the next release if you have that option.

Scope creep and its impact on quality

Scope creep is directly linked to the project triangle. And it’s the project management term for when your project magically acquires new functionality in its objectives. A little can be expected; too much can be bad.

Scope creep affects the quality side of the triangle. And whether your product will be fit for purpose — the more requirements you can deliver, the better the quality of the product.

Your options to deal with scope creep are to add time, so you include the added functionality. Spend more money to manage the extra work. Or to cut the quality, by cutting out non-essential functionality or requirements.

Why does the project triangle matter?

If you’re running a big project, you’ll probably have a change board in place to review change requests and the impact on scope. They’ll determine which changes will be approved.

But even smaller projects, or those with limited resources, can have a change process running to keep an eye on scope creep, and the impact of cost and time constraints. This will help you to understand the shifts in the triangle. You’ll be able to get clarity around the impact on the schedule, budget and quality control. And this will help you make better decisions.

A balancing act

Balancing the triangle elements while you manage a project will help you deliver a fit for purpose outcome; on time and on budget while adapting to changes along the way.

Change is inevitable. But you’ll find it easier to deal with it and prioritise effectively when you clearly understand the constraints and manage their impact on the other areas of the project.

The time/cost/quality triangle is a simple concept. Knowing why it matters can add massive value to your project.

The Time/Cost/Quality Triangle

The time/cost/quality triangle is a simple way to understand the inevitable constraints on a project. See how changing one element affects the others and learn how to manage those changes to help you prioritise and make better project decisions.

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