3.5 Quality Management
Key Takeaways
- Quality is defined as the degree to which a set of inherent characteristics fulfills requirements — conformance to requirements and fitness for use
- Prevention (keeping errors out of the process) is preferred over inspection (keeping errors out of the hands of customers)
- The Cost of Quality includes the cost of conformance (prevention + appraisal) and the cost of nonconformance (internal + external failure)
- Key quality tools include cause-and-effect diagrams, control charts, flowcharts, histograms, Pareto charts, scatter diagrams, and check sheets
- Plan Quality Management, Manage Quality, and Control Quality are the three quality processes that span planning, executing, and monitoring
Quality Management
Quality management ensures the project satisfies the needs for which it was undertaken. Quality on the CAPM exam means conformance to requirements and fitness for use — not just producing the best possible product.
Quality Concepts
| Concept | Definition |
|---|---|
| Quality | The degree to which a set of inherent characteristics fulfills requirements |
| Grade | A category assigned to deliverables with the same functional use but different technical characteristics |
| Precision | Consistency of repeated measurements (how close values are to each other) |
| Accuracy | Correctness of a measured value (how close to the true value) |
Key Distinction: Low quality is always a problem. Low grade may be acceptable. A software product can be high quality (no bugs) but low grade (limited features), which is acceptable. Low quality (many bugs) regardless of grade is not acceptable.
Quality Management Processes
| Process | Process Group | Focus |
|---|---|---|
| Plan Quality Management | Planning | Identify quality requirements and standards |
| Manage Quality | Executing | Audit quality requirements and incorporate lessons learned (quality assurance) |
| Control Quality | Monitoring & Controlling | Monitor and verify deliverables meet standards (quality control) |
Manage Quality vs. Control Quality
| Manage Quality (QA) | Control Quality (QC) |
|---|---|
| Focus on processes | Focus on deliverables |
| Proactive — prevents defects | Reactive — detects defects |
| Ensures processes are followed | Inspects outputs for compliance |
| Process audits | Product inspection and testing |
| "Are we using the right processes?" | "Do the deliverables meet requirements?" |
Cost of Quality (CoQ)
The Cost of Quality represents the total cost of all efforts related to quality:
| Category | Type | Examples |
|---|---|---|
| Prevention Costs | Conformance | Training, process documentation, equipment, design reviews |
| Appraisal Costs | Conformance | Testing, inspections, audits, peer reviews |
| Internal Failure Costs | Nonconformance | Rework, scrap, retesting (defects found before delivery) |
| External Failure Costs | Nonconformance | Warranty, recalls, liability, lost reputation (defects found after delivery) |
Exam Principle: Prevention is less costly than inspection. Investing in prevention and appraisal (conformance costs) reduces internal and external failure costs (nonconformance costs).
The Seven Basic Quality Tools
| Tool | Purpose | When to Use |
|---|---|---|
| Cause-and-Effect Diagram (Fishbone/Ishikawa) | Identify root causes of problems | Brainstorming potential causes |
| Control Chart | Monitor process stability over time | Tracking process performance |
| Flowchart | Visualize process steps and decision points | Understanding process flow |
| Histogram | Show frequency distribution of data | Understanding data distribution |
| Pareto Chart | Identify the vital few causes (80/20 rule) | Prioritizing problems |
| Scatter Diagram | Show relationships between two variables | Analyzing correlations |
| Check Sheet (Tally Sheet) | Collect data in a structured format | Gathering frequency data |
Additional Quality Concepts
Continuous Improvement
- Plan-Do-Check-Act (PDCA): Deming cycle for iterative improvement
- Kaizen: Japanese philosophy of continuous, incremental improvement
- Six Sigma: Data-driven approach to eliminate defects (3.4 defects per million opportunities)
Statistical Concepts
- Normal Distribution: Bell curve where 68.3% falls within ±1σ, 95.5% within ±2σ, and 99.7% within ±3σ
- Control Limits: ±3 standard deviations from the mean (set by the process)
- Specification Limits: Customer requirements (set by the customer)
- Out of Control: A point outside control limits or a non-random pattern within them
Which quality principle states that it is better to prevent defects than to find them through inspection?
Which quality tool uses the 80/20 rule to identify the most significant causes of defects?
Match each quality management concept with its correct definition:
Match each item on the left with the correct item on the right