Perform Quality Control

Perform Quality Control is the process of monitoring and recording results of executing the quality activities to assess performance and recommend necessary changes. Quality control is performed throughout the project. Quality standards include project processes and product goals. Project results include deliverables and project management results, such as cost and schedule performance. Quality control is often performed by a quality control department or similarly titled organizational unit. Quality control activities identify causes of poor process or product quality and recommend and/or take action to eliminate them. See Figures 8-10 and 8-11.

The project management team should have a working knowledge of statistical quality control, especially sampling and probability, to help evaluate quality control outputs. Among other subjects, the team may find it useful to know the differences between the following pairs of terms:

• Prevention (keeping errors out of the process) and inspection (keeping errors out of the hands of the customer).

• Attribute sampling (the result either conforms or does not conform) and variables sampling (the result is rated on a continuous scale that measures the degree of conformity).

• Tolerances (specified range of acceptable results) and control limits (thresholds, which can indicate whether the process is out of control).

.1 Project management plan .2 Quality metrics .3 Quality checklists .4 Work performance measurements .5 Approved change requests .6 Deliverables .7 Organizational process assets

.1 Cause and effect diagrams .2 Control charts .3 Flowcharting .4 Histogram .5 Pareto chart .6 Run chart .7 Scatter diagram .8 Statistical sampling .9 Inspection .10 Approved change requests review

Outputs

.1 Quality control measurements .2 Validated changes .3 Validated deliverables .4 Organizational process assets updates .5 Change requests .6 Project management plan updates .7 Project document updates

Figure 8-10. Perform Quality Control: Inputs, Tools & Techniques, and Outputs

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Cost Quality Project Management
Figure 8-11. Perform Quality Control Data Flow Diagram

8.3.1 Perform Quality Control: Inputs

.1 Project Management Plan

The project management plan described in Section 4.2.3.1 contains the quality management plan, which is used to control quality. The quality management plan describes how quality control will be performed within the project.

.2 Quality Metrics

Described in Section 8.1.3.2.

.3 Quality Checklists

Described in Section 8.1.3.3.

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.4 Work Performance Measurements

Work performance measurements are used to produce project activity metrics to evaluate actual progress as compared to planned progress. These metrics include, but are not limited to:

• Planned vs. actual technical performance,

• Planned vs. actual schedule performance, and

• Planned vs. actual cost performance. .5 Approved Change Requests

As part of the Perform Integrated Change Control process a change control status update will indicate that some changes are approved and some are not. Approved change requests can include modifications such as defect repairs, revised work methods and revised schedule. The timely implementation of approved changes needs to be verified.

.6 Deliverables

Described in Section 4.3.3.1.

.7 Organizational Process Assets

The organizational process assets that can influence the Perform Quality Control process include, but are not limited to:

• Quality standards and policies,

• Standard work guidelines, and

• Issue and defect reporting procedures and communication policies.

8.3.2 Perform Quality Control: Tools and Techniques

The first seven of these tools and techniques are known as Ishikawa's seven basic tools of quality.

.1 Cause and Effect Diagrams

Cause and effect diagrams, also called Ishikawa diagrams or fishbone diagrams, illustrate how various factors might be linked to potential problems or effects. Figures 8-12 and 8-13 are examples of cause and effect diagrams. A possible root cause can be uncovered by continuing to ask "why" or "how" along one of the lines. "Why-Why" and "How-How" diagrams may be used in root cause analysis. Cause and effect diagrams are also used in risk analysis (Section 11.2.2.5).

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Time

Machine

Method

Material

\ \ \ \

Major Defect

/ / / /

Energy

Measurement

Personnel

Environment

Effect

Potential Causes

Effect

Figure 8-12. Classic Sources of Problems to Consider

Figure 8-12. Classic Sources of Problems to Consider

Figure 8-13. Environment Bone Expanded by Brainstorming .2 Control Charts

Control charts are described in Section 8.1.2.3. In this process, the appropriate data is collected and analyzed to indicate the quality status of project processes and products. Control charts illustrate how a process behaves over time and when a process is subject to special cause variation, resulting in an out-of-control condition. They graphically answer the question: "Is this process variance within acceptable limits?" The pattern of data points on a control chart may reveal random fluctuating values, sudden process jumps, or a gradual trend in increased variation. By monitoring the output of a process over time, a control chart can help assess whether the application of process changes resulted in the desired improvements.

When a process is within acceptable limits it is in control and does not need to be adjusted. Conversely, when a process is outside acceptable limits, the process should be adjusted. Seven consecutive points outside the upper or lower control limits indicate a process that is out of control. The upper control limit and lower control limit are usually set at ±31, where 11 is one standard deviation.

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Described in Section 8.1.2.7, flowcharting is used during Perform Quality Control to determine a failing process step(s) and identify potential process improvement opportunities. Flowcharting is also used in risk analysis (Section 11.2.2.5).

.4 Histogram

A histogram is a vertical bar chart showing how often a particular variable state occurred. Each column represents an attribute or characteristic of a problem/situation. The height of each column represents the relative frequency of the characteristic. This tool helps illustrates the most common cause of problems in a process by the number and relative heights of the bars. Figure 8-14 is an example of an unordered histogram showing causes of late time entry by a project team.

Causes of Late Time Entry

__[

Insufficient Time

Management Direction

Process Documentation

System Failure

Travel

22

3

30

3

16

Figure 8-14. Histogram

.5 Pareto Chart

A Pareto chart, also referred to as a Pareto diagram, is a specific type of histogram, ordered by frequency of occurrence. It shows how many defects were generated by type or category of identified cause (Figure 8-15). Rank ordering is used to focus corrective action. The project team should address the causes creating the greatest number of defects first.

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Pareto diagrams are conceptually related to Pareto's Law, which holds that a relatively small number of causes will typically produce a majority of the problems or defects. This is commonly referred to as the 80/20 principle, where 80% of the problems are due to 20% of the causes. Pareto diagrams can also be used to summarize various types of data for 80/20 analyses.

.6 Run Chart

Similar to a control chart without displayed limits, a run chart shows the history and pattern of variation. A run chart is a line graph that shows data points plotted in the order in which they occur. Run charts show trends in a process over time, variation over time, or declines or improvements in a process over time. Trend analysis is performed using run charts and involves mathematical techniques to forecast future outcomes based on historical results. Trend analysis is often used to monitor:

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• Technical performance. How many errors or defects have been identified, and how many remain uncorrected?

• Cost and schedule performance. How many activities per period were completed with significant variances?

.7 Scatter Diagram

A scatter diagram (Figure 8-16) shows the relationship between two variables. This tool allows the quality team to study and identify the possible relationship between changes observed in two variables. Dependent variables versus independent variables are plotted. The closer the points are to a diagonal line, the more closely they are related. Figure 8-16 shows the correlation between the timecard submission date and the number of days traveling per month.

CD LU

c s .2

Timecard Submission in Days (Ideal is zero)

▲ ▲

▼ ▼

♦ ♦ ♦

CO -R

Total Travel Days in the Month

Figure 8-16. Scatter Diagram

.8 Statistical Sampling

Described in Section 8.1.2.6. Samples are selected and tested as defined in the quality plan.

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An inspection is the examination of a work product to determine whether it conforms to documented standards. The results of an inspection generally include measurements and may be conducted at any level. For example, the results of a single activity can be inspected, or the final product of the project can be inspected. Inspections may be called reviews, peer reviews, audits, or walkthroughs. In some application areas, these terms have narrow and specific meanings, inspections are also used to validate defect repairs.

.10 Approved Change Requests Review

All approved change requests should be reviewed to verify that they were implemented as approved.

8.3.3 Perform Quality Control: Outputs

.1 Quality Control Measurements

Quality control measurements are the documented results of quality control activities in the format specified during quality planning.

.2 Validated Changes

Any changed or repaired items are inspected and will be either accepted or rejected before notification of the decision is provided. Rejected items may require rework.

.3 Validated Deliverables

A goal of quality control is to determine the correctness of deliverables. The results of the execution quality control processes are validated deliverables. Validated deliverables are an input to Verify Scope (5.4.1.4) for formalized acceptance.

.4 Organizational Process Assets Updates

Elements of the organizational process assets that may be updated include, but are not limited to:

• Completed checklists. When checklists are used, the completed checklists become part of the project's records (Section 4.1.1.5).

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• Lessons learned documentation. The causes of variances, the reasoning behind the corrective action chosen, and other types of lessons learned from quality control are documented so they become part of the historical database for both the project and the performing organization. Lessons learned are documented throughout the project life cycle, but at a minimum, during project closure.

.5 Change Requests

If the recommended corrective or preventive actions or a defect repair requires a change to the project management plan, a change request (Section 4.4.3.1) should be initiated in accordance with the defined Perform Integrated Change Control (4,5) process.

.6 Project Management Plan Updates

Elements of the project management plan that may be updated include, but are not limited to:

• Quality management plan, and

• Process improvement plan.

.7 Project Document Updates

Project documents that may be updated include, but are not limited to, quality standards.

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