# Reference value

The reference value is in many fields of a particular numerical value which to compare is used.

## General

For example, all information in percent is based on a reference value. If this is not specified, misunderstandings or contradictions can easily arise. If 20% of the population of a country is affected by poverty , the population (total population) is the reference value:

${\ displaystyle {\ text {Percentage}} = {\ frac {\ text {Comparison value}} {\ text {Reference value}}} \ cdot 100 \, \%}$.

The comparison value is the number of people affected by poverty, the reference value is the total population, the percentage is called the poverty rate .

## Use in physics and technology

In the physical-technical context, the following uses are highlighted in the specialist literature :

• In measurement technology as well as in quality assurance and statistics, the reference value is a clearly defined value to which reference is made to define a result deviation ( measurement deviation ). The reference value can be, for example, the upper limit of a measuring range , the scale length or any other clearly defined value. In particular, depending on the definition or agreement, it can be the true , correct or expected value .
• On closer inspection, many material constants turn out to be dependent on influencing variables . Then they are given at a fixed reference value. As far as deviations of the constants can be indicated, these are determined from the reference value. Example: Influence of temperature of the specific resistance .

The variable to be compared is often related to the reference value via a difference (e.g. for the measurement deviation), but the values ​​can also be linked via a quotient (e.g. for the ratio) or a quotient of the difference to the Reference value (e.g. for the relative error limit ).

## Further subject-specific uses

In various specialist fields, the term reference value, possibly also called reference value, is defined in a special way, or it is replaced by a whole reference system of many individual reference values.

Such reference values ​​can be: