What is the measurement error

When measuring it is difficult to find the true value of a particular parameter. Even if the determination of the value of the value is made with the help of proven high-quality tools, there will be a measurement error that numerically becomes equal to the deviation of the true value from that obtained experimentally. In its essence, it characterizes the accuracy of the measurements. There are several types of this value.

Thus, the measurement error can be static and dynamic. In the first case, it is calculated in determining the values of constant values under conditions under which transient processes in the elements of devices and converters will be completed. In the second case, the parameter is determined in varying (dynamic) conditions. For measuring instruments, this value is calculated by subtracting from the error of the measuring means determined in the dynamic conditions of the static error, which corresponds to the value of the value at a particular time.

Also, the measurement error can be systematic and random. In the first case, the deviation from the true value remains constant or regularly changing when several repeated measurements of the same parameter are made. There are many reasons for the appearance of this component. In the most general case, this type of error is a function:

• Measured value;
• The values influencing the value of the measured parameter (temperature, humidity, stress and other factors are most often referred to here);
• Time.

The systematic error does not change modulo and sign in the case of several parallel experiments. It depends on a number of factors:

1. Inaccuracy of instruments, which manifests itself in the deviation of the parameters of measuring instruments from nominal properties. Due to this, an instrumental measurement error is generated, which is calculated for each specific instrument.

2. Imperfection or mistakenness of the choice of the method of measurement: methodical error.

3. The human factor, that is, the subjective error.

4. The influence of certain factors from the external environment.

A random component arises as a result of the combined action of a number of causes that appear randomly at each specific measurement, for example, as a result of pulsation of a constant supply voltage. Therefore, the manifestation of this component is difficult to foresee, and therefore to exclude. To minimize the effect of a random error on the final result of a measurement, several approaches are performed, the results of which determine the average value of the sought parameter.

The error depends on the method of determining the desired value. The error in direct measurements is determined not as indirect. In the first case, the value of some value is directly in the process of measurement, that is, directly, and then, according to a known formula, a deviation is calculated. In the second case, a certain parameter is determined by experience, knowing which, you can calculate the desired value. Only after this, the error of indirect measurements can be calculated.

It is also worth noting that it can be presented in various forms. In particular, the absolute, relative and reduced are distinguished. In the first case, the difference between the nominal value and the actual value of the measured quantity is found. In the second - the ratio of absolute error and true value. The reduced measurement error is determined by dividing the absolute value by a value that is conventionally accepted as constant for a particular measurement interval. What form of presentation you choose will depend on the particular experiment.