• Control Charts compares the normality and the actual state: The range normally has a middle line. Therefore an unbalanced distribution of values may also indicate, that the process should be improved. This might be identified by a value convergence or by the Rule of Seven (= 7 value on one side of the middle)

(5.3) Perform Quality Control

(5.3.1) Process Input

... generated by predecessor processes

... introduced by external units

  • Organizational process assets

(5.3.2) Process Definition

Perform Quality Control is the process for "monitoring specific project results to determine whether the comply with relevant quality standards and identifying ways to eliminate causes of unsatifactory performance" (comp. PMBOK3, p. 179). "Quality standards include project processes and product goals" (comp. PMBOK3, p. 190).

Perform quality control (and perform quality assurance) has to deal with the following antinomies:

  • Prevention versus Inspection: Avoid defects versus repair defects.
  • Attribute sampling versus variables sampling: yes or no descisions versus gradual differentiations.
  • Special causes versus common causes: unsual events versus normal variations
  • Tolerances versus control limits: range of result floatings versus acceptable process ranges

(comp. PMBOK3, p. 191).

The subject Quality operates on the base of other quality concerning concepts

(5.3.3) Tools and Techniques

PMBOK Mentioned Methods

  • Cause and effect diagram also known as Ishikawa diagram  or Fishbone diagram is a special technique for documenting multiple aspects as cause of an effect / defect. (comp. PMBOK3, p. 192).
  • Control charts indicate "[...] whether or not a process is stable" by offering an upper limit and a lower limit, which often are generated by  using +/-3 sigma or Six Sigma. The main idea is that the process  must be improved / adjusted if values are hurting the limits (comp. PMBOK3, pp. 192f).
  • Flow charting is the representation of a process as flow chart for analyzing the points of annoyances (comp. PMBOK3, p. 193).
  • Histogram generates a pictures "[...] showing the distribution of variables" (over the time) by signaling "the relative frequency of characteristic" (comp. PMBOK3, p. 194).
  • Pareto chart sorts the defects by frequency of occurence. As consequence of the 80:20-rule ("[...] 80 percent of the problems are due to 20 percent auf causes") one can identify those defects which should be repaired first (comp. PMBOK3, p. 195).
  • Run chart "[...] is a line graph that shows data points plotted in the order in which they occur". Therefore it is a method for investigating changes (comp. PMBOK3, p. 196).
  • Scatter diagram "[...] shows the pattern of realationships between two variables" and indicates interferences (comp. PMBOK3, p. 196).
  • Statistical sampling means the selection and investigation of reprensentative data subsets (populations). The degree of expressivity of this method might be increased by take more than one sample or by variable samples (comp. PMBOK3, p. 196).
  • Inspection "[...] is the examination of a work product to determine wether it conforms to standards" (comp. PMBOK3, p. 196).
  • Defect Repair Review "[...] is an action [...] to ensure that product defects are repaired". It's the proof that defect repairs have succesfully been executed (comp. PMBOK3, p. 196).

Open Source Tools

  • NN

(5.3.4) Process Output

  • Quality Control Measurements are generated and documented results of investigations.
  • Validated Defect Repair is the documented proof that a (recommended and approved) defect repair has succesfully been executed.
  • Updates of the Quality Baseline can be generated by the given approved change requests.
  • Recommended Corrective Actions are the result of inspection or other methods by which process problems and solutions can be identified.
  • Recommended Preventive Actions are the result of inspection and so on by which process problems and solutions have been identified.
  • Requested Changes may be evoked by recommended corrective or preventive actions.
  • Recommended Defect Repair is a result of inspection and so on by which product problems and solutions have been identified.
  • Updates of the Organizational Process Assets are generated by documenting more widely usable checklist and lessons learned.
  • Validated Deliverables are the result of the proof that the generated results / deliverables of the projct fullfill the quality requirements. The results may be used by the process of Scope Verification
  • Updates of the Project Management Plan are are implicitely generated by updates of the quality baseline.

(comp. PMBOK3, pp. 197f).

(5.3.5) Output Using Successor Processes

Successors using the initially generated output as own input(1):

Processes using the updates as input(2):

  1. For details see FAQ::Q001:1
  2. For details see FAQ::Q001:2