Amalija Horvatić Novak

Measurement: A Very Short Introduction

The book Measurement: A Very Short Introduction, by David J. Hand, attempts to familiarize the readers with the importance of measurement in almost all areas of human activity. The book is not targeted exclusively toward the academic community; it aims to reach a wider audience attempting to gain basic insight or expand upon their current knowledge about the measurement process. The book is divided into 7 chapters, which examine major topics of measurement, from the goal of measurement to measurement scales and efficiency measurements. In the first chapter the author provides readers with a short overview of the historical process of the evolution of measurement. He emphasizes the fact that the need for precise measurements appeared very early on in the history of human civilization. Various measurement systems have been developed throughout human history. The first measurements were used in the contexts of ancient marketplaces—where people met to trade goods and services—and of tax and debt collection. At that time it was very common for each individual settlement to have its own measurement system. Measurement quantities also differed from country to country; although identical in name, they were distinguished from one other in terms of their proportions. As time went by, with the ever stronger development of transportation networks, disparate world regions became better connected. This increased connectivity and paved the way for the standardization of previously disparate measurement quantities that were used to conduct the same measurements in the different regions. The author illustrates well this pressing need for change when he gives the example of the attempted exchange of goods between villagers of different settlements wherein the volume or weight of trade goods in the two villages were incompatible. This introduction to the history of measurement allows us to better understand the measurement process and appreciate its significance. The author uses his historical overview as both a reminder and a critique of the fact that even today, with the emergence of industry 4.0, the world still does not have a unified system of measurement. This situation affects primarily the physical quantities of length and volume. It is still the case that the kilometer is predominantly used as a measuring unit in traffic in Europe, with its corresponding equivalent in the United States being the mile. A good example of the drawbacks of the existence of these two parallel systems of measurement is the fact that an American visitor to Europe, taking a car from the United States, would have a very difficult time of navigating Europe’s highways, where the speed limits are denoted in km/h while the car would be able to provide information about the driver’s speed expressed in mph. If we were to imagine a concrete case wherein, upon entering a European highway, an American was met with a sign denoting a speed limit of 80 measurement units, in the European case this would denote the value of 80 kilometers per hour (km/hr). An American travelling the European highways at 80 miles per hour (mph) would be in immediate violation of the law, because 80 mph equals 129 km/hr. This would be information the visitor could not be privy to on the spot, which would put the visitor and other passengers in immediate danger. A similar situation arises when one is calculating volume of pints, considering the fact that despite their shared history, British and American pints do not represent the same volume. According to the SI measurement system, if a American citizen were to make a purchase of one pint of liquid of goods, he or she would be delivered an extra 95 mL, while if the situation were reversed, the British buyer would come up short. It is evident that these discrepancies in the various measurement

Examples of measurement uncertainty evaluations in accordance with the revised GUM

The paper presents examples of the evaluation of uncertainty components in accordance with the current and revised Guide to the expression of uncertainty in measurement (GUM). In accordance with the proposed revision of the GUM a Bayesian approach was conducted for both type A and type B evaluations.The law of propagation of uncertainty (LPU) and the law of propagation of distribution applied through the Monte Carlo method, (MCM) were used to evaluate associated standard uncertainties, expanded uncertainties and coverage intervals. Furthermore, the influence of the non-Gaussian dominant input quantity and asymmetric distribution of the output quantity y on the evaluation of measurement uncertainty was analyzed. In the case when the probabilistically coverage interval is not symmetric, the coverage interval for the probability P is estimated from the experimental probability density function using the Monte Carlo method. Key highlights of the proposed revision of the GUM were analyzed through a set of examples.