What type of probability is based on personal judgment rather than calculations?

Subjective probability is grounded in personal judgment or belief rather than in statistical calculations or empirical data. It reflects an individual's or group's personal assessments or opinions on the likelihood of an event occurring. This form of probability acknowledges that personal experiences, intuition, and individual perceptions can all influence the perceived likelihood of an event.

For example, someone might estimate the probability of rain tomorrow based on their experiences with local weather patterns and their understanding of current weather conditions, rather than relying on meteorological data. This makes subjective probability particularly useful in situations where quantitative data may be scarce or where the decision-maker has specialized knowledge.

In contrast, objective probability is derived from statistical calculations and is typically based on historical data, while statistical probability focuses on the outcomes based on a defined sample space. Relative probability often compares the likelihood of events, but it does not involve personal judgment. Each of these alternatives relies on different methodologies that contrast sharply with the personal approach taken in subjective probability.