Quality Management
What the domain is really testing
Quality management covers planning quality standards, quality assurance (process-focused, preventive, audit-driven) and quality control (product-focused, inspection-driven, corrective). Candidates must know the difference between quality (conformance to requirements) and grade (category of features), and that low grade with high quality can be acceptable while the reverse is not. Understand cost of quality, the seven basic tools (cause-and-effect, Pareto, control charts, histogram, scatter, flowchart, check sheet), and continuous improvement cycles.
Concepts to hold firmly
- Prevention is cheaper than inspection, which is cheaper than failure.
- Control charts distinguish common-cause variation (adjust the process) from special-cause variation (investigate the point).
- Pareto analysis targets the few causes producing most defects.
- Acceptance criteria must be measurable and agreed before work starts.
Traps
Questions frequently swap assurance and control. Auditing a process is assurance; testing a deliverable is control. Another trap presents a control chart point outside the limits and asks whether to change the process - no, investigate the special cause first. Beware answers that respond to defects by adding more inspection when the root cause lies in the process; that is a prevention fix. Also, "gold plating" is adding unrequested features, which is a quality failure, not generosity.
Rule of thumb
Ask: am I checking how we work (assurance) or checking what we produced (control)?
Worked example
A test team finds 30 defects; Pareto shows 22 stem from one interface specification. The correct action is to correct the specification and the review process (prevention), not to add a second inspection stage after build.