Accuracy refers to the conformity of the measurement and the actual value and tells you nothing about the quality of the instrument. The instrument can be of high quality and still cannot match the actual value. In the example above, it was assumed that the purpose of the clock was to measure the location of the sun when it seems to be moving above the sky. However, in our time zone system, the sun is only just above the head at 12 o`clock if you are in the center of the time zone. If you are on the eastern periphery of the time zone, the sun is just above you around 11:30 a.m., while on the western periphery, the sun is just above you around 12:30 p.m. On both sides, the value measured at 12 o`clock therefore does not correspond to the phenomena according to which the sun is at the local zenith, and we could complain that the clock is not accurate. Here, the accuracy of the clock display is influenced by our time zone system and not by a watch defect. Suppose your classmate has measured the width of a standard notebook and shows the result as 8.53 ± 0.08 inches. By declaring uncertainty as 0.08 inches, your classmate confidently asserts that any reasonable measurement of this sheet of paper by other experimenters gives a value of no less than 8.45 inches and no more than 8.61 inches. In the first half of the twentieth century, the concept of insecurity reached new heights with the discovery of quantum mechanics. In the quantum world, insecurity is not an inconvenience; It is a state of being. For example, the decay of a radioactive element is inherently an uncertain event.
We could then estimate the accuracy of the measurement under ideal conditions at half one mm (0.5 mm), as the measurements would probably indicate that the edge of the paper is closest to the same marking each time. To make a statement about our uncertainty, we would then need a level of confidence, in this case it would be qualitative: we are very confident that repeated measurements will be above or below average within a period of 0.5 mm. However, it`s pretty easy to imagine that you could be sure that the desk doesn`t move more than ten centimeters (~five inches) away from your measurement. You may have experience with measuring strips. And based on this experience, you are sure that your tape measure could not be stretched five inches from its good length. If you don`t have that confidence, maybe ten inches or a foot would make you confident. After the measurement, you could say, “This desk has no more than 1.35 m and is no shorter than 0.95 m.” You could make this statement with confidence. The scientist would write L = 1.20 ± 0.15 m. The format is “value more or less uncertainty”. In science, an important indication of confidence in a measure is the number of significant numbers reported. Morimoto reported his measurement to one decimal place (34.6 m/s) because his instrumentation supported this accuracy. .