Popular Project Management Approaches: Waterfall, Agile, Lean, Six Sigma and Lean Six Sigma

10 min readMar 9, 2022

A project management methodology is a set of guiding principles and processes for owning a project through its life cycle. Project management methodologies help guide project managers throughout a project with steps to take, tasks to complete, and principles for managing the project overall.

1. Linear means the previous phase or task has to be completed before the next can start. A linear approach would work well for a project like building a house. completing each step in order and sticking to the agreed-upon specific results and being able to deliver just what the client ordered.

Linear projects don’t require many changes during development and have a clear sequential process. If you stick to the plan, it’s likely you’ll finish your tasks within the time schedule and all other criteria.

2. Iterative, more flexible approach where some of the phases in tasks will overlap or happen at the same time that other tasks are being worked on. In an iterative approach, plans remain flexible and you’re able to make adjustments as you go along.

Iterative projects allow for more flexibility and anticipate changes. You’re able to test out parts of the project to make sure they work before the final result is delivered, and you can deliver parts of the project as they are completed, rather than waiting for the entire project to be done.

Popular Project Management Approaches

1. Waterfall:

is a traditional methodology in which tasks and phases are completed in a linear, sequential manner, and each stage of the project must be completed before the next begins. The project manager is responsible for prioritizing and assigning tasks to team members. In Waterfall, the criteria used to measure quality is clearly defined at the beginning of the project.

2. Agile:

involves short phases of collaborative, iterative work with frequent testing and regularly-implemented improvements. Some phases and tasks happen at the same time as others. In Agile projects, teams share responsibility for managing their own work. Scrum and Kanban are examples of Agile frameworks, which are specific development approaches based on the Agile philosophy.

Scrum is an Agile framework that focuses on developing, delivering, and sustaining complex projects and products through collaboration, accountability, and an iterative process. Work is completed by small, cross-functional teams led by a Scrum Master and is divided into short Sprints with a setlist of deliverables.
Kanban is both an Agile approach and a tool that provides visual feedback about the status of the work in progress through the use of Kanban boards or charts. With Kanban, project managers use sticky notes or note cards on a physical or digital Kanban board to represent the team’s tasks with categories like “To do,” “In progress,” and “Done.”

3. Lean:

uses the 5S quality tool to eliminate eight areas of waste, save money, improve quality, and streamline processes. Lean’s principles state that you can do more with less by addressing dysfunctions that create waste. Lean implements a Kanban scheduling system to manage production.

4. Six Sigma:

involves reducing variations by ensuring that quality processes are followed every time. The Six Sigma method follows a process-improvement approach called DMAIC, which stands for define, measure, analyze, improve, and control.

5. Lean Six Sigma:

is a combination of Lean and Six Sigma approaches. It is often used in projects that aim to save money, improve quality, and move through processes quickly. Lean Six Sigma is also ideal for solving complex or high-risk problems. The 5S quality tool, the DMAIC process, and the use of Kanban boards are all components of this approach.

Despite their differences, all of these project management methodologies require communication and collaboration among various teams and aim to deliver projects on time and within budget.

Waterfall or Traditional Approach

Refers to the sequential ordering of phases. You complete one at a time down the line like a waterfall starting at the top of a mountain and travelling to the bottom. Waterfall has a linear approach.

Follow an ordered set of steps that are directly linked to clearly defined expectations, resources, and goals that are not likely to change.
Initiating, planning, executing, which includes managing and completing tasks, and closing.
We use this approach, when the phases of the project are clearly defined or when there are tasks to complete before another can begin, or when changes to the project are very expensive to implement once it’s started.
A well-thought-out traditional approach to managing a project can help you reach your desired outcome with as little pain as possible during the project implementation.
Following this approach will help you identify the right people and tasks, plan accordingly to avoid any hiccups along the way, create room for documenting your plans and progress, and enable you to hit that goal.

Agile Approach

Methodologies that are entirely built for change and flexibility.
The term agile means being able to move quickly and easily. It also refers to flexibility, which means being willing and able to change and adapt. Projects that use an Agile approach often have many tasks being worked on at the same time, or in various stages of completion which makes it an iterative approach.
Rather than having to always go in order or wait for one phase to end before starting the next, Agile project phases overlap and tasks are completed in iterations, which in Scrum, are called sprints. (Scrum is a form of Agile. Sprints are short chunks of time usually one to four weeks where a team works together to focus on completing specific tasks.)
Agile is more of a mindset than just a series of steps or phases. It’s concerned with building an effective, collaborative team that seeks regular feedback from the client so that they can deliver the best value as quickly as possible and adjust as changes emerge.
Projects that are best suited for an Agile approach are those where the client has an idea of what they want but doesn’t have a concrete picture in mind, or they have a set of qualities they’d like to see in the end result but aren’t as concerned with exactly what it looks like.
Another indicator that a project may benefit from Agile is the level of high uncertainty and risk involved with the project.
This allows the team to get feedback early on about what works and what doesn’t, make adjustments along the way, and reduce wasted efforts.

Waterfall and Agile Comparison

1. Waterfall

Project manager’s role: The project manager serves as an active leader by prioritizing and assigning tasks to team members.
Scope: Project deliverables and plans are well-established and documented in the early stages of initiating and planning. Changes go through a formal change request process.
Schedule: Follows a mostly linear path through the initiating, planning, executing, and closing phases of the project.
Cost: Costs are kept under control by careful estimation upfront and close monitoring throughout the life cycle of the project.
Quality: The project manager makes plans and clearly defines criteria to measure quality at the beginning of the project.
Communication: The project manager continually communicates progress toward milestones and other key indicators to stakeholders, ensuring that the project is on track to meet the customer’s expectations.
Stakeholders: The project manager continually manages and monitors stakeholder engagement to ensure the project is on track.

2. Agile

Project manager’s role: Agile project manager (or Scrum Master) acts primarily as a facilitator, removing any barriers the team faces. The team shares more responsibility in managing their own work.
Scope: Planning happens in shorter iterations and focuses on delivering value quickly. Subsequent iterations are adjusted in response to feedback or unforeseen issues.
Schedule: Time is organized into phases called Sprints. Each Sprint has a defined duration, with a setlist of deliverables planned at the start of the Sprint.
Cost: Costs and schedule could change with each iteration.
Quality: The team solicits ongoing stakeholder input and user feedback by testing products in the field and regularly implementing improvements.
Communication: The team is customer-focused, with consistent communication between users and the project team.
Stakeholders: Team frequently provides deliverables to stakeholders throughout the project. Progress toward milestones is dependent upon stakeholder feedback.

Lean methodology (Lean Manufacturing)

The main principle in Lean methodology is the removal of waste within an operation. By optimizing process steps and eliminating waste, the only value is added at each phase of production.

The Lean Manufacturing methodology recognizes eight types of waste within an operation: defects, excess processing, overproduction, waiting, inventory, transportation, motion, and non-utilized talent. In the manufacturing industry, these types of waste are often attributed to issues such as:

Lack of proper documentation
Lack of process standards
Not understanding the customers’ needs
Lack of effective communication
Lack of process control
Inefficient process design
Failures of management

Implement Lean project management when you want to use limited resources, reduce waste, and streamline processes to gain maximum benefits.

You can achieve this by using the pillars of the Lean 5S quality tool. The term 5S refers to the five pillars that are required for good housekeeping: sort, set in order, shine, standardize, and sustain. Implementing the 5S method means cleaning up and organizing the workplace to achieve the smallest amount of wasted time and material. The 5S method includes these five steps:

Sort: Remove all items not needed for current production operations and leave only the bare essentials.
Set in order: Arrange needed items so that they are easy to use. Label items so that anyone can find them or put them away.
Shine: Keep everything in the correct place. Clean your workspace every day.
Standardize: Perform the process, in the same way, every time.
Sustain: Make a habit of maintaining correct procedures and instil this discipline in your team.

Within the Lean methodology, 5S helps you boost performance.

The final concept of Lean uses a Kanban scheduling system to manage production. The Kanban scheduling system, or Kanban board, is a visualization tool that enables you to optimize the flow of your team’s work. It gives the team a visual display to identify what needs to be done and when. The Kanban board uses cards that are moved from left to right to show progress and help your team coordinate the work.

Kanban boards and 5S are core principles of the Lean methodology. They can help you successfully manage your project.

Six Sigma methodology

Six Sigma is a methodology used to reduce variations by ensuring that quality processes are followed every time. The term “Six Sigma” originates from statistics and generally means that items or processes should have 99.9996% quality. The seven key principles of Six Sigma are:

Always focus on the customer.
Identify and understand how the work gets done. Understand how work really happens.
Make your processes flow smoothly.
Reduce waste and concentrate on value.
Stop defects by removing variation.
Involve and collaborate with your team.
Approach improvement activity in a systematic way.

Use this methodology to find aspects of the product or process that are measurable like time, cost, or quantity. Then inspect that measurable item and reject any products that do not meet the Six Sigma standard. Any process that created unacceptable products has to be improved upon.

Lean Six Sigma

it was discovered that the two methodologies could be combined to increase benefits. The tools used in Lean, such as Kanban boards and 5S, build quality in processes from the beginning. Products developed using Lean methods are then inspected or tested using Six Sigma standards. The products that do not meet these standards are rejected.

The largest difference between these methodologies is that Lean streamlines processes while Six Sigma reduces variation in products by building in quality from the beginning and inspecting products to ensure quality standards are met. You may find that one of these two methods — or using them both together — can improve the efficiency of your projects.

Lean and Six Sigma

It’s a combination of two-parent methodologies, Lean and Six Sigma. The uses for Lean Six Sigma are common in projects that have goals to save money, improve quality, and move through processes quickly.

It also focuses on team collaboration which promotes a positive work environment. The idea is that when your team feels valued, motivation and productivity increase and the whole process functions more smoothly.
There are five phases in the Lean Six Sigma approach. They are Define, Measure, Analyze, Improve, and Control, commonly known as DMAIC. (DMAIC is a strategy for process improvement, meaning you’re trying to figure out where the problems are in the current process and fix them so that everything runs more smoothly. The goal of each step is to ensure the best possible results for your project. DMAIC process can be used to solve any business problem.)

DMAIC

Define the project goal and what it will take to meet it. This first phase is very similar to the initiation phase of traditional project management. You’re going to need to define the project goal and talk to stakeholders about expectations for the project. Measure how the current process is performing. In order to improve processes, DMAIC focuses on data. Here you want to map out the current process and locate exactly where the problems are and what kind of effect the problems have on the process(defining tells you what to measure).
Measure: Then you’ll set a plan for how you’ll get that data and how often to measure it. This could look something like having the company generate reports on a weekly, monthly, quarterly basis. In other situations, you might have employees or customers fill out surveys or look at inventory, shipping, and tracking records, things like that (measuring tells you what to analyze).
Analyze: You’ll begin to identify gaps and issues. From your data, you’ll have a strong understanding of causes and solutions to get to the next stage (analyzing tells you what to improve).
Improve: This is the point where you present your findings and get ready to start making improvements (improving tells you what to control).
Control: You’ve gotten the process and project to a good place, and now it’s time to implement it and keep it there. Controlling is all about learning from the work you did up front to put new processes and documentation in place and continue to monitor so the company doesn’t revert back to the old, inefficient way of doing things.

Lean Six Sigma and the DMAIC approach are ideal when the project goal includes improving the current process to fix complex or high-risk problems like improving sales, conversions, or eliminating a bottleneck, which is when things get backed up during a process.

Following the DMAIC process prevents the likelihood of skipping important steps and increases the chances of a successful project. As a way for your team to discover best practices that your client can use going forward, it uses data and focuses on the customer or end-user to solve problems in a way that builds on previous learning so that you can discover effective permanent solutions for difficult problems.