# Probability of occurrence

Probability of occurrence (also probability of damage , or frequency of damage ) describes the statistical expected value or the estimated probability of a certain event occurring in a certain period in the future . The probability of occurrence is a term used in the calculation of probability or statistics and is specified in percent or as a value between 0 and 1.

• 0 means: the event will never occur; impossible event
• Values ​​close to 0; unlikely event
• Values ​​close to 1; probable event
• A value of 1 means that the event will definitely occur; sure event .

The probability that at least one of different stochastically independent events will occur is calculated using de Morgan's formulas .

A distinction must be made between the probability for an individual case and the overall probability.

Example: The probability that someone will pick 6 correct numbers in the lottery 6 out of 49 is 1 / 13,983,816 and is therefore very low (unlikely event). If, however, a large number of games are played (e.g. 40 million games), the probability of the occurrence of the event (= probability of occurrence) increases in the vicinity of 1 (probable event). So it is very likely that at least one tip will win the next time the game is played.

It is one of the psychological factors of occupational safety that people always count on the individual probability, which is usually only given as a statistical mean (illusion of one's own inviolability). Due to the combination of different factors (dangerous conditions, favorable conditions) the probability of occurrence can be considerably higher. (see also probability neglect )

Likewise, the likelihood increases for individuals if they are exposed to the same risk more often (analogous to the number of games in the lottery: it can be increased if more people play and if people play more often or start several games at the same time).

In occupational health and safety and actuarial mathematics , undesirable events ( damage or accidents ) are considered; this is also referred to as the probability of damage . The value of the probability of occurrence is part of the damage risk . A calculable risk should range between the residual risk and the marginal risk . In occupational safety this would be the area of "safe work" .

In the risk assessment z. B. With the risk matrix according to Nohl, the probability of occurrence is specified in categories and "sensibly estimated".

## Individual evidence

1. Ash, James L. / Russell, Bruce E. / Rommell, Robert R .: Improved subsurface investigation for highway tunnel design and construction; v.1: Subsurface investigation system planning . Ed .: Dept. of Transportation. Springfield, Virginia December 27, 1974 p. 107 .
2. ^ Journal for the entire insurance science . In: Journal for the entire insurance science . tape 1 . ES Mittler & Sohn., Berlin 1901, p. 317-318 .
3. Thiemecke, Hartmut / Nohl, Jörg: Systematics for carrying out hazard analyzes, research report 536 . Ed .: Federal Institute for Occupational Safety and Health. Dortmund 1987, p. 105 .