Make your own free website on

8.3 Quality Control


Quality Control involves monitoring specific project results to determine if they comply with relevant quality standards and identifying way to eliminate causes of unsatisfactory results. Project results include both product results such as deliverables and management results such as cost and schedule performance.

The project management team should have a working knowledge of statistical quality control, including the differences between:

  • Prevention (keeping errors out of a process) and inspection (keeping errors out of the hands of the customer).
  • Attribute sampling (the result conforms or it does not) and variable sampling (the result is rated on a continuous scale that measures the degree of conformity).
  • Special causes (unusual events) and random causes (normal process variation).
  • Tolerances (the result is acceptable if it falls within the range specified by the tolerance) and control limits (the process is in control if the result falls within the control limits).

8.3.1 Inputs

  1. Work results
  2. Quality management plan
  3. Operational definitions
  4. Checklists

8.3.2 Tools & Techniques

  1. Inspection
  2. Control charts
  3. Pareto diagrams
  4. Statistical sampling
  5. Flowcharting
  6. Trend analysis

8.3.3 Outputs

  1. Quality improvement
  2. Acceptance decisions
  3. Rework
  4. Completed checklists
  5. Process adjustments






8.3.1 Quality Control - Inputs Work results

Work results include both process results and product results. Information about the planned and expected results should be available along with information about the actual results. Quality management plan

Refer quality management plan. Operational definitions

Refer operational definitions. Checklists

Refer to checklists.


Return to Top of Page

8.3.2 Quality Control - Tools and techniques Inspection

Inspection includes activities such as measuring, examining and testing undertaken to determine whether results conform to requirements. Inspections may be conducted at any level and variously called reviews, product reviews, audits and walk-throughs. Control charts

Control charts are a graphic display of the results, over time, of a process. They are used to determine if a process is "in control". The process may be changed to provide improvements but should not be adjusted when it is in control.

Control charts can also be used to monitor cost and schedule variances, volume and frequency of scope changes, errors in project documents, or other management results to help determine if a "project management process" is in control. Pareto diagrams

A Pareto diagram is a histogram, ordered by frequency of occurrence, that shows how many results were generated by type or category of identified cause. Rank ordering is used to guide corrective action - the project team should take action to fix the problems that are causing the greates number of defects first. Statistical sampling

Statistical sampling involves choosing part of a population of interest for inspection. Appropriate sampling can reduce the cost of quality control. Flowcharting

Refer flowcharting. Trend analysis

Trend analysis involves using mathematical techniques to forecast future outcomes based on historical results. Trend analysis is often used to monitor:


Return to Top of Page

8.3.3 Quality Control - Outputs Quality improvement

Refer quality improvement. Acceptance decisions

The items inspected will be either accepted or rejected. Rejected items may require rework. Rework

Rework is action taken to bring a defective or non-conforming item into compliance with requirements or specifications. Rework, especially unanticipated rework is a frequent cause of project overruns in most application areas and should be minimised. Completed checklists

When checklists are used, the completed checklists should become part of the project's records. Process adjustments

Process adjustments involve immediate corrective or preventative action as a result of quality control measurements. In some cases, the process adjustment may need to be handled according to procedures for overall change control.


Return to Top of Page