quality management and lean six sigma

Design Quality

The inherent value of a product in the marketplace; fitness for purpose.

Conformance Quality

The degree to which a product or service meets design specifications.

Quality at the Source

Workers are responsible for doing the job correctly the first time and stopping the process when problems occur.

Four Costs of Quality

Prevention costs, appraisal costs, internal failure costs, and external failure costs.

Prevention Costs

Costs to prevent defects, including training, quality procedures, and product redesign.

Appraisal Costs

Costs of inspections, testing, and quality audits.

Internal Failure Costs

Costs of defects found within the system, including scrap, rework, and lost production time.

External Failure Costs

Costs of defects reaching customers, including warranties, complaints, liability claims, and lost goodwill.

Quality Is Free

Investing in defect prevention can reduce overall quality costs.

Normalization of Deviance

When repeated violations of rules or safety procedures become accepted because nothing bad happens initially.

Chesterton's Fence

Understand the original purpose of a rule or procedure before eliminating it.

Six Sigma

A method focused on reducing process variation and defects.

Lean

A philosophy focused on eliminating waste from process flow.

Lean Six Sigma

An improvement approach combining waste reduction with reduced variation and defects.

Six Sigma Performance

Approximately 3.4 defects per million opportunities, or 99.99966% accuracy.

Defects per Million Opportunities (DPMO)

A measure of defects relative to the total number of opportunities for defects.

DPMO Formula

[Defects / (Units × Opportunities per Unit)] × 1,000,000

Defects per Unit (DPU) Formula

Total Defects / Total Units

Higher Sigma Level

Indicates fewer defects and greater process capability.

Accuracy

How close a measurement is to the true or desired value.

Precision

How closely repeated measurements agree with one another.

DMAIC

Define, Measure, Analyze, Improve, Control.

Weighted Scoring Model (WSM)

A decision-making tool that compares alternatives using weighted criteria.

Weighted Scoring Model Formula

Multiply each criterion score by its assigned weight and add the results.

Check Sheet

A structured form used to consistently collect and tally data.

Pareto Chart

A chart ranking problem categories by frequency or impact to identify the most important contributors.

Pareto Principle (80/20 Rule)

Approximately 80% of problems come from 20% of causes.

Run Chart

A time-ordered graph used to identify trends, shifts, cycles, and unusual patterns.

Control Chart

A time-ordered graph with statistical control limits used to monitor process stability.

Scatter Diagram

A graph displaying the relationship between two measured variables.

Correlation vs. Causation

Correlation indicates a relationship between variables but does not prove one causes the other.

Flowchart

A diagram showing the sequence of steps, decisions, inputs, and outputs in a process.

Cause-and-Effect Diagram (Fishbone)

A diagram organizing potential causes of a problem to help identify root causes.

Six Major Fishbone Categories

Man, Machine, Method, Material, Measurement, and Mother Nature (Environment).

Histogram

A graph showing the frequency distribution of continuous numerical data using adjacent bins.

Cost of Poor Quality (COPQ)

Money lost because of defects and inefficiencies, such as scrap, rework, and returns.

Flow Time

Elapsed time from the beginning to the end of a process for a unit.

Cycle Time

Time between successive completions of units in a process.

Define Phase

The DMAIC phase focused on identifying the problem, customer requirements, scope, and project objectives.

DMAIC Tollgate Review

A formal checkpoint used to evaluate project progress and readiness to move forward.

SIPOC

Suppliers, Inputs, Process, Outputs, Customers.

SIPOC Purpose

Provides a shared high-level understanding of a process and its boundaries.

SIPOC Development Order

Process, Outputs, Customers, Inputs, Suppliers.

SIPOC DMAIC Phase

Define phase.

Project Charter

A formal document outlining an improvement project's problem, objectives, scope, and responsibilities.