5.3 Measurement Terminology

During implementation, services and products are sampled and measured to determine if the quality is within control limits for the requirements and to analyze possible causes for any quality variations. A separate quality control group often does this evaluation, and knowledge of a few process measurement terms is necessary to understand their reports. Several of these terms are similar, and it is valuable to know the distinction between them.

Project teams can identify the control limits of the product or process. The size of the range between those limits is the tolerance. Tolerances are often written as the mean value, plus or minus (±) the tolerance.

Tools are selected that can measure the samples closely enough to determine if the measurements are within control limits and whether any trends emerge. Each measurement tool has its own tolerances.

The choice of tolerance directly affects the cost of quality (COQ). In general, it costs more to produce and measure products that have small tolerances. The costs associated with making products with small tolerances for variation can be very high and not proportional to the gains. For example, suppose the cost of evaluating each screen as it is created in an online tutorial is greater than delivering the product and fixing any issues after the fact. In that case, the COQ may be too high, and the instructional designer will tolerate more defects in the design.

Statistics

Determining how well products meet grade requirements is done by taking and interpreting measurements. Statistics, the mathematical interpretation of numerical data, are useful when interpreting large numbers of measurements to determine how well the product meets a specification (when the same product is being made repeatedly). Measurements made on product samples must be within control limits, which are the upper and lower extremes of allowable variation. It is up to the project team to design a process that will consistently produce products between those limits.

Suppose a process is designed to produce a product of a certain size or another measured characteristic. In that case, it is impossible to control all the small factors that can cause the product to differ slightly from the desired measurement. Some of these factors will produce products with larger measurements than desired, and some will have the opposite effect. If several random factors affect the process, they tend to offset each other, and the most common results are near the middle of the range; this phenomenon is called the central limit theorem.

If the range of possible measurement values is divided equally into subdivisions, referred to as bins, the measurements can be sorted, and the number of measurements that fall into each bin can be counted. The result is a frequency distribution that shows how many measurements fall into each bin. If the effects causing the differences are random and tend to offset each other, the frequency distribution is called a normal distribution, which resembles the shape of a bell with edges that flare out. The edges of a theoretical normal distribution curve get very close to zero but do not reach zero.

Quality Assurance

The purpose of quality assurance is to create confidence that the quality plan and controls are working correctly. Time must be allocated to review the original quality plan and compare that plan to how quality is ensured during the project’s implementation.

Process Analysis

The flowcharts of quality processes are compared to the processes followed during actual operations. If the plan was not followed, the process is analyzed, and corrective action is taken. The corrective action could be to educate the people involved on how to follow the quality plan, or it could be to revise the plan.

The experiments that sample products/processes and collect data are examined to see if they are following statistically valid sampling techniques and that the measurement methods have small enough tolerances to detect variation within control limits.

Because projects are temporary, there are fewer opportunities to learn and improve within a project, especially if it has a short duration. But even in short projects, the quality manager should have a way to learn from experience and change the process for the next project of a similar complexity profile.

Quality assurance: Aims to build confidence in the user that quality standards and procedures are being followed. This is done by an internal review of the plan, testing, and revision policies. Or by an audit of the same items performed by an external group or agency.

Quality audits: A quality audit reviews the quality plan to determine whether the project activities comply with organizational and project policies, processes, and procedures.

Quality reviews: A formal procedure for reviewing a product, system or service against quality criteria set forth by the project organization. Quality reviews are planned and documented inspections of the project. They represent a significant effort in terms of required resources. If the reviews identify errors, the cost of quality becomes less since the earlier an error is identified, the better the project’s success. Examples of quality reviews include:

• Expert reviews
• Peer reviews
• Team reviews
• Walk-through reviews
• Formal reviews
• Management reviews
• Process reviews

Inspections: An inspection is a formal evaluation involving measurements and tests. Quality must be plan in and prevented, and not inspected.

Gold Plating

Gold plating is all about giving the customer extra value to the product (more functionality, higher-quality parts, more scope than required, higher performance). Some organizations have a policy that promotes adding value to customers and going beyond to fulfill their requests, although advanced quality thinkers and PMI do not recommend it. The team’s impression of what is valued by the customer and what the customer does not want is often called gold plating. Gold plating can be done on certain projects and may not be done on certain others. This creates a gap in customers’ expectations, and hence gold plating is not recommended.

Continuous Improvement

Continuous Improvement is about continuously looking for small improvements in the process. The term “Continuous Improvement” also means Kaizen in Japanese, where Kai means Change and Zen means for the better.

Quality reports: A quality report includes quality management issues, recommendations for corrective actions, and a summary of findings from quality control activities. It may consist of recommendations for processes, projects, and product improvement.

Just In Time (JIT)

The concept of JIT involves having the suppliers deliver raw materials just when they are needed, thus reducing inventory to close to zero. JIT has supplemented reduction in high inventory costs, which is unnecessary.

Total Quality Management (TQM)

This philosophy encourages companies and their employees to focus on continuously improving the quality of their products and business practices at every level of the organization.

Responsibility For Quality

The ultimate responsibility of the product or project quality lies with the project manager and project team members. However, the organization has a responsibility relating to quality.

Agile projects often use quality development techniques

Agile projects often use quality development techniques, many of which originated in Extreme Programming (XP) and were used in software projects. These techniques are now being adapted for use in other project types. Some of these techniques are Test-driven development (TDD), Pair programming, Peer review, Collective code ownership, and Continuous integration.