No physical quantity can be measured absolutely accurately. Each time, making any measurement and calling the result obtained, it is possible to judge the absolute accuracy of the obtained value with only a certain degree of probability. Moreover, the value of this probability is negligible due to the fact that any measured value falls into a certain interval, which determines the absolute error.
In the general case, the error is understood as the deviation of the obtained value of the measured quantity from its true value. The realities of the world around us are such that no tool, no matter how accurate it may be, can convey an absolutely accurate meaning. Therefore, when measuring, it is said that the absolute error formed a certain interval, and the measured value is located in the interval between its boundaries.
How is the interval in which the true value of the measured value is located? The first parameter is the accuracy of the instrument. Depending on the manufacturing technology of the measuring instrument, its properties and characteristics, one or another error value arises. Of course, the higher the accuracy of the device, ceteris paribus, the more expensive it is, but at the same time it provides the observer with a more accurate measurement result. The choice of measuring instrument and its accuracy depends on the requirements of the problem being solved. Not all calculations require high accuracy, and therefore it is important to choose the right device so that the results do not affect the overall measurement result.
Another parameter that affects accuracy is the correct use of the measuring device. Moreover, it plays a very important role in the measurement! Any person taking measurements should be able to handle the measuring instrument correctly. Otherwise, he risks not only getting incorrect results, but even ruining the device. Therefore, before using a measuring tool (especially high-tech), it is important to read the instructions, understand the principle of operation and the device configuration diagram,
and only after that proceed with the measurements.
The third parameter is the direct reading of the instrument readings. If the device is equipped with a digital display, then the absolute error by this criterion is zero. In the case when the device has a measuring scale, the measurement error increases, because an observer may simply incorrectly take readings due to the physiological characteristics of a person's vision. As a rule, in such cases, the error interval is increased by the division price of the device.
The last key parameter is associated with the processing method of the measurement. And first of all, it depends on the correctness of the rounding of the obtained value. It should be noted that any rounding already initially distorts the true value, however, again, when carrying out the procedure for processing the results, it is important to take into account the influence on the truth of the solution of the problem by applying one or another method of processing the value.
The four parameters listed above are only external, the most obvious factors that influence the formation of the interval of deviation of the obtained value from the real one. In reality, the absolute error depends on a set of parameters, which, depending on the type of problem, the influence of the environment, and the type of instrument used, can have a tremendous effect on the measurement results.
In conclusion, we note how the relative and absolute errors are interconnected. The first is the ratio of the absolute error to the measured value. Therefore, if the absolute error is a certain value with the same dimension as the measured quantity, then the relative error shows what proportion the error is from the true result of the quantity.