Concepts of Metrology and Quality Testing
Senior 2 · Entrepreneurship
Concepts of Metrology and Quality Testing
Lesson 4 of 4
22 min
A supermarket in Kigali, a hospital buying supplies, or a buyer in Nairobi will not stock a product just because the seller says it is good. They want proof that it meets a recognised standard. For a Rwandan maker of juice, honey, soap or bricks, passing quality tests and earning a certification mark can be the difference between selling at the roadside and selling across the region.
A standard is a document, agreed by experts and approved by a recognised body, that sets out requirements for a product, process or service: what to measure, how to measure it, and the acceptable limits. Rwanda uses Rwanda Standards (RS), East African Standards (EAS) shared with the other EAC countries, and international standards such as those of ISO.
The Rwanda Standards Board (RSB) is the public body responsible for standards in Rwanda. It develops and publishes standards, tests products in its laboratories, certifies products and management systems, and provides metrology services (calibrating and verifying measuring instruments).
The S-Mark (Standardisation Mark) is RSB's product certification mark. A business applies to RSB; RSB inspects the production site and tests samples against the relevant standard; if the product complies, the business may print the S-Mark on it. RSB then keeps monitoring, and certification must be renewed. For the business, the S-Mark builds customer trust, opens doors to supermarkets, public tenders and regional markets, and reduces complaints and returns.
Written by Ganzaa. The tolerance is an illustrative figure, not taken from a published standard. A beekeepers' cooperative in Nyamagabe labels its jars “Net mass 500 g” and sets a tolerance of ±8 g. It samples five jars from a batch and measures their net masses: 502 g, 498 g, 489 g, 505 g and 500 g.
Tip
Memory hook: S-S-T-C-D-C-C. Standard, Sample, Test, Compare, Decide, Correct, Certify. In exams, say that sampling must be random and that test instruments must be calibrated.
Solution: An agreed document, approved by a recognised body, that sets requirements for a product, process or service, including what to measure and the acceptable limits.
Solution: Quality control inspects finished products to find defects; quality assurance manages the whole process to prevent them. Quality control happens at the end; quality assurance runs throughout production.
Solution: So that it represents the whole batch; a hand-picked sample could hide faulty items.
Solution: The range is 195 g to 205 g, so only the 207 g bar fails (it is over the limit).
Solution: Customers trust the product more; supermarkets and public buyers are more willing to stock it; it helps the company sell in other EAC countries; fewer complaints and returns.
Summary
Sources and credits
The honey example and the practice items are written by Ganzaa.
This lesson adapts CC BY-SA material and is shared under CC BY-SA 4.0.
