Quality, Quality Assurance and Quality Control

1. What is Quality?

A “Quality Software” is bugs free, delivered on time with in the budget, meets customer expectation and is maintainable.

Quality is a subjective term. It depends on 'Who the customer is'. The concept of quality establishes the foundation for an understanding of continuous process improvement.

Quality is much more than absence of defects which allows us to meet customer’s expectations.

Quality can be viewed in two ways, quality in fact and quality in perception. Quality in perception is the customer’s point of view and quality in fact is supplier’s point of view.

Quality in fact:

(Customer’s view)

• Doing the right things
• Doing the right way
• Doing it right first time
• Doing it on time.

Quality in Perception:

(Suppliers view)

• Delivering the right product on time.
• Satisfying the customer’s needs.
• Meeting the customer’s expectations
• Treating every customer with integrity, courtesy and respect.

 Why Quality?

Quality is the most important factor affecting an organization’s long-term performance. Quality is the way to achieve improved productivity and competitiveness in any organization.

Cost of quality: Cost of quality is the cost incurred in tuning a product in to a quality product.

The three categories of costs associated with producing quality products are:

1. Prevention Cost: Money required to prevent errors and to do the job right the first time. This category includes money spent on establishing methods and procedures, training workers, acquiring tools and planning for quality. It is spent before the product is actually built.
2. Appraisal Cost: Money spent to evaluate the completed product against               requirements. Appraisal cost includes the cost of inspection, testing and reviews. This money is spent after the product is built but before it is shipped to the user.
3. Failure Cost: This is the cost associated with defective products that have been delivered to the user or moved in to production. Some failure costs involve repairing products to make them fit as per requirements.

Cost of Quality = Prevention Cost + Appraisal Cost + Failure Cost.

2. Quality Assurance:

The function of software quality that assures that the standards, processes, and procedures are appropriate for the project and are correctly implemented.

QA would also measure the effectiveness of the Verification processes by tracking defects that were missed by QC during Verification.

QA is defect prevention oriented.

This is usually done through out the life cycle.

Examples: Reviews and Audits

3. Quality Control:

The function of software quality that checks that the project follows its standards, processes, and procedures, and that the project produces the required internal and external (deliverable) products.

Concentrates on specific products.

QC is defect detection and correction oriented.

This is usually done after the product is build.

Example: Testing at various levels