Conditional Probability: What Is It?
The possibility that one result will arise from several alternative possibilities is an unconditional probability. The phrase describes the probability that an event will occur regardless of whether other events or circumstances exist.
An example of an unconditional probability is the likelihood that snow will fall in Jackson, Wyoming, on Groundhog Day, without considering past weather trends and climate data for northwest Wyoming in early February.
One may compare and contrast unconditional probability with conditional probability.
Knowing What Unconditional Probability Is
By summing up all of the event’s conceivable outcomes and dividing by the entire number of possible outcomes, one may calculate the unconditional probability of an occurrence.
P(A) = Total Number of Possible Outcomes / Number of Times ‘A’ Occurs
Also referred to as marginal probability, unconditional probability calculates the likelihood of an event without considering any information gleaned from past or outside occurrences. This likelihood always stays the same since it doesn’t consider fresh facts.
Conversely, conditional probability refers to the possibility of an event or result happening but only when another event or previous result occurs. To calculate the conditional probability, multiply the probability of the previous event by the updated likelihood of the subsequent or conditional occurrence.
P(A|B), which represents the “probability of A given B,” is a common way to represent conditional probability. Joint probability, which expresses the “probability of A and B,” or P(A ∩ B), as the chance of two or more possibilities happening concurrently, is not the same as unconditional probability. In essence, it includes A and B’s unconditional probabilities.
Unconditional Probability Example
As a fictitious financial example, let’s look at a collection of stocks and their returns. A stock may have a positive return if it is a winner or a negative return if it is a loss. Let us assume that A and B are winners of the five stocks while C, D, and E are losers. Thus, what is the unconditional likelihood of selecting a profitable stock? Given that two of the five potential outcomes will result in a winner, the unconditional probability is 40% (2 / 5 = 0.4) = 2 successes divided by the total number of possibilities (2 / 5 = 5).
Conclusion
- Unconditional probability expresses the likelihood that an event will transpire without considering potential influences or past results.
- For example, the unconditional probability of a fair coin flip ending in heads is 50%, irrespective of the number of coin flips that preceded it or any other event.
- Marginal probability is another name for unconditional probability.
