Stop 04 · Process Modeling & AnalysisTopics · 7/9

Process Improvement Techniques (Lean, Six Sigma Overview)

In short

Lean and Six Sigma come from factories, but banks, hospitals and IT teams use them every day. One cuts waste, the other cuts mistakes, and together they make processes faster and more reliable.

Lean focuses on eliminating waste and maximizing value; Six Sigma focuses on reducing variation and defects through statistical rigor — both provide structured methodologies for process improvement.

The purple blob flips a dosa on a big flat griddle at a street food stall.

Think of it like this

The busy dosa stall

Lean is the dosa man keeping batter, oil and chutney within arm's reach, so he never walks to the back. Six Sigma is making every dosa the same thickness and crispness, so no customer sends one back. Less waste, less variation.

Watch it happen

Two ways to improve a process

Lean

Removes waste and waiting
Asks 'does this step add value?'
Tools: value stream maps, 5S

Six Sigma

Reduces variation and defects
Uses data and statistics
Method: DMAIC, five phases

Use Lean when work is slow, Six Sigma when results are inconsistent. Many companies combine them as Lean Six Sigma.

The big ideas

What you need to know

Eight kinds of waste

Lean names them: defects, overproduction, waiting, unused talent, transport, inventory, motion and extra processing. Remembered as DOWNTIME.

Six Sigma's target

The name refers to a quality level of about 3.4 defects per million chances. The real point is measuring and cutting variation.

Belts show training level

Yellow, Green and Black Belts show how deep someone's Six Sigma training goes. BAs often start with Yellow or Green.

BA's role

Map the process, gather the data, find the waste or defects and help the team test improvements.

How it works

DMAIC, Six Sigma's five phases

1
Define
State the problem, the customer and the goal, like 'cut invoice errors by half'.
2
Measure
Collect data on how the process performs today. No guessing.
3
Analyse
Find the root causes of defects using data and tools like fishbone diagrams.
4
Improve
Test fixes for the root causes and measure whether they work.
5
Control
Lock in the gains with checklists, monitoring and updated procedures.

Save yourself the pain

Common mistakes

Oops

Using Lean as an excuse to cut staff.

Do this instead

Lean is about removing wasted effort so people can do valuable work. Framing it as job cuts kills cooperation.

Oops

Running a full Six Sigma project on a tiny problem.

Do this instead

Match the effort to the problem. Sometimes a quick process walk and one change is enough.

Your mission

Spot the waste

~25 min

Quick check

Orders are processed quickly, but about one in ten has a wrong address. Which approach fits best first?

Go deeper

1Learn the concept of the 8 wastes in Lean methodology.
2Read a high-level overview of Six Sigma's DMAIC framework (Define, Measure, Analyze, Improve, Control).
3Understand these are deep specializations — this roadmap gives you enough to speak the vocabulary, not full mastery.