prioritodennäköisyys

Prioritodennäköisyys, meaning "prior probability" in English, refers to the initial degree of belief in a proposition before any evidence is considered. It is a fundamental concept in Bayesian statistics and probability theory. Prior probabilities are subjective, reflecting an individual's or a group's existing knowledge or assumptions about an event or hypothesis. They can be based on historical data, expert opinions, or even be deliberately set to be non-informative if there is little prior knowledge.

In Bayesian inference, the prior probability is updated using Bayes' theorem when new data becomes available. This updated probability is called the posterior probability, which represents the revised belief after incorporating the evidence. The choice of prior can significantly influence the posterior, especially when the amount of data is limited. Different types of priors exist, such as informative priors that encode strong beliefs and uninformative priors that represent a more neutral stance. The concept of prior probability is crucial for making informed decisions and updating beliefs in the face of new information.