Randomness in the real world

Repeated experiments and statistical regularity

One way to approach the notion of probability is through the phenomenon of statistical regularity. There are many repeating situations in nature for which we can predict in advance, from previous experiences, roughly what will happen, but not exactly what will happen. We say in such cases that the occurrences are random. The reason that we cannot predict future events exactly may be that (i) we do not have enough data about the condition of the given problem, (ii) the laws governing a progression of events may be so complicated that we cannot undertake a detailed analysis, or possibly (iii) there is some basic indeterminacy in the physical world. Whatever the reason for the randomness, a definite average pattern of results may be observed in many situations leading to random occurrences when the situation is recreated a great number of times. For example, if a fair coin is flipped many times, it will turn up heads on about half of the flips.

Another example of randomness is the response time of a web (i.e.,WorldWideWeb or WWW) access request you may send over the Internet in order to retrieve some information from a certain website. The amount of time you have to wait until you receive a response will not be precisely predictable, because the total round trip time depends on a number of factors.