# identification number

A key figure is a measure that is used for quantification and is based on a specification for the quantitative, reproducible measurement of a variable or a condition or process.

## General

Key figures condense facts or causal relationships with the help of absolute numbers , equations , formulas or index values . The viewer (the public , media , analysts ) should be able to form opinions , make assessments , establish rankings or make decisions based on key figures .

Strictly speaking, a key figure in itself is not meaningful; What is meant is always a parameter, i.e. the product of characters (e.g. letters , also in combination with mathematical characters or special characters for ratings [e.g. AA +], or number for numerical information) and a unit of measurement (e.g. . ° C , , meter ).

## species

Key figures can be roughly divided into

A key figure value is the value of the key figure at a certain point in time (e.g. number of employees on December 31, 2007) or over a specified period (e.g. profit in a fiscal year).

For many key figures there are typically suffixes such as - proportion , - coefficient , - factor , degree, index, - coefficient , - quota , - ratio , number , rate and the like, some of which are special types of key figures according to the metrological standards are reserved.

## electronics

In electronics, there are characteristics for ohmic resistors, transistors, tubes and diodes, among other things.

## Measurement theory

In measurement theory, a key figure is quantitative, essential information. By selection and grouping, data becomes information , with key figures determining the essential facts. They are used for analysis and control. For example, performance indicators classify the performance of machines or athletes.

## statistics

Various key figures exist in mathematical statistics . With these key figures it is possible, for example in descriptive statistics , to get a good overview of distributions , mean values, etc. with just a few quantitative data . Examples of statistical key figures are:

## Quality management

In quality management, one strives for improvements in processes and results. To do this, you set goals and measure the degree of goal achievement with key figures. Depending on the goal, key figures can be, for example, the number of articles in Wikipedia or, better still, the increase in the number of articles or, even better, the increase in the number of articles worth reading. In management, for example, employee satisfaction or the number of successfully implemented suggestions for improvement can be a key figure.

## Criticism, possible errors and risks

The focus on one key figure - instead of a holistic key figure system - harbors the risk of incorrect interpretation and even wrongdoing; A typical example of this is the body count , which was used, for example, in the Vietnam War. Linking the number of enemy soldiers killed with the target achievement system of the military superiors led to misinterpretations such as the inclusion of civilian victims up to violations of martial law.

Ultimately, a key figure is always only a quantitative indicator that requires a qualitative review and interpretation with regard to the achievement of the intended goal.