Probability is especially important in statistics because of the many principles and procedures based upon this concept. Indeed, probability plays a special role in all our lives, because we use it to measure uncertainty. We are continually faced with decisions leading to uncertain outcomes, and we rely on probability to help us make our choice. Think of the planned outdoor activities, such as picnics or boating, you canceled because the chance of bad weather seemed too likely. Remember those nights before examinations when you decided not to study some topics, because they probably would not be covered on the test?
A probability is a numerical value that measures the uncertainty that a particular event will occur. The probability of an event ordinarily represents the proportion of times under identical circumstances that the outcome can be expected to occur. We refer to this value as the event’s long-run frequency of occurrence. The probability that the head side will slow when a fair coin is tossed is 1/2. This can be verified experimentally by tossing a coin several times and observing that “heads” occur about one-half of those times. continue reading…
