3.4.4 - Quality assurance and quality control

Quality and the consequences of failure

Quality depends on fitness for purpose and consistency in meeting the requirements promised to the customer.

A budget product can be high quality if it reliably performs its advertised function. A premium product can be poor quality if it frequently fails. Requirements may include safety, durability, accurate dimensions, taste, correct information or courteous and dependable service. A restaurant's food and its waiting time can both affect the customer's judgement; an accurate bank statement is as important to service quality as a physical product's finish.

Poor quality creates costs within operations. Materials may be scrapped, work repeated and machines stopped to investigate failures. Labour and capacity used for rework cannot supply new saleable output. For example, a furniture maker that discovers a weak joint after painting has already spent materials and labour on an item requiring repair.

Failure can then affect other stakeholders. Customers may seek refunds, leave negative reviews, switch suppliers or experience harm. Employees may face complaints, unsafe processes or pressure to correct faults. Suppliers may receive disputed payments or urgent replacement requests. Owners may receive lower returns if warranty costs rise or future sales fall. Safety failures can also create legal and reputational consequences, although the exact response depends on the defect and circumstances.

The competitive effect depends on expectations and alternatives. A business differentiated by reliability is particularly exposed if failures contradict its promise. If rivals supply dependable products at a similar price, customers can switch readily. The immediate cost of replacing one item may therefore be smaller than the longer-term loss of trust and repeat sales. Quality decisions should examine both internal failure costs and external customer consequences rather than count only defective units.

On 27 February 2024, Toyota announced a US recall covering approximately 381,000 model-year 2022–2023 Tacoma trucks. Welding debris could allow axle-retaining nuts to loosen, and dealers would inspect and repair affected vehicles without charging customers. A manufacturing defect therefore created later inspection and corrective work as well as a safety risk, illustrating why prevention and customer consequences matter together. Toyota's recall announcement.

Prevention and inspection

Quality assurance and quality control address quality at different points in the process and can be used together.

Quality assurance builds quality into how work is done. The business can define standards, train staff, maintain equipment, assess suppliers and design checks or procedures at important stages. Employees understand their responsibility for meeting requirements and addressing causes of faults. In furniture production, accurate joint specifications, staff training and reliable cutting settings help prevent weak joints from being made.

Quality control checks whether outputs meet the required standard and identifies faults. Inspection or testing might occur during production or at completion, using all items or a suitable sample. An inspector testing finished chairs can stop a defective chair reaching a customer. However, the defect has already occurred, and identifying it does not automatically remove its cause. Sampling also creates a possibility that a faulty item is not inspected or detected.

Assurance is therefore associated with prevention, while control is associated with detection and correction. This does not mean assurance eliminates every defect or that control must only occur at the final stage. A business may inspect incoming components, test work at intermediate stages and feed the findings back into an assurance system. Some safety-critical or complex products require checks even when prevention is strong.