Unlikely

Unlikely is a term used to describe a situation or event that is not expected to happen or is not probable. It is often used in probability theory, statistics, and risk assessment to quantify the chance of an event occurring.

Definition

In common usage, the term "unlikely" is used to describe an event that is not expected to happen. In probability theory, an event is considered unlikely if its probability is less than 0.5. This is based on the assumption that an event with a probability of 0.5 is equally likely to happen or not happen.

Use in Probability Theory

In probability theory, the term "unlikely" is used to describe an event with a low probability of occurring. Probability is a measure of the likelihood that an event will occur, and is expressed as a number between 0 and 1, where 0 indicates that the event will not occur, and 1 indicates that the event will definitely occur. An event with a probability of less than 0.5 is considered unlikely.

Use in Statistics

In statistics, the term "unlikely" is used in a similar way to probability theory. However, in statistics, the term is often used in the context of null hypothesis testing. If the probability of observing a particular result, given that the null hypothesis is true, is less than a predetermined significance level (often 0.05), then the result is considered unlikely under the null hypothesis.

Use in Risk Assessment

In risk assessment, the term "unlikely" is used to describe a risk that is not expected to occur. This is based on a combination of the probability of the event occurring and the potential impact of the event. A risk that is unlikely to occur may still be considered significant if the potential impact is high.

See Also

• Probability theory
• Statistics
• Risk assessment
• Likelihood function
• Odds