Randomness means different things in various fields. Commonly, it means lack of pattern or predictability in events.
The Oxford English Dictionary defines "random" as "Having no definite aim or purpose; not sent or guided in a particular direction; made, done, occurring, etc., without method or conscious choice; haphazard." This concept of randomness suggests a non-order or non-coherence in a sequence of symbols or steps, such that there is no intelligible pattern or combination.
Applied usage in science, mathematics and statistics recognizes a lack of predictability when referring to randomness, but admits regularities in the occurrences of events whose outcomes are not certain. For example, when throwing two dice and counting the total, we can say that a sum of 7 will randomly occur twice as often as 4. This view, where randomness simply refers to situations where the certainty of the outcome is at issue, applies to concepts of chance, probability, and information entropy. In these situations, randomness implies a measure of uncertainty, and notions of haphazardness are irrelevant.
The fields of mathematics, probability, and statistics use formal definitions of randomness. In statistics, a random variable is an assignment of a numerical value to each possible outcome of an event space. This association facilitates the identification and the calculation of probabilities of the events. A random process is a sequence of random variables describing a process whose outcomes do not follow a deterministic pattern, but follow an evolution described by probability distributions. These and other constructs are extremely useful in probability theory.
Randomness is often used in statistics to signify well-defined statistical properties. Monte Carlo methods, which rely on random input, are important techniques in science, as, for instance, in computational science.
Random selection is a method of selecting items (oftentimes called units) from a population where the probability of choosing a specific item is the proportion of those items in the population. For example, if we have a bowl of 100 marbles with 10 red (and any red marble is indistinguishable from any other red marble) and 90 blue (and any blue marble is indistinguishable from any other blue marble), a random selection mechanism would choose a red marble with probability 1/10. Note that a random selection mechanism that selected 10 marbles from this bowl would not necessarily result in 1 red and 9 blue. In situations where a population consists of items that are distinguishable, a random selection mechanism requires equal probabilities for any item to be chosen. That is, if the section process is such that each member of a population, of say research subjects, has the same probability of being chosen then we can say the selection process is random. Random selection can be an official method to resolve tied elections in some jurisdictions and is even an ancient method of divination, as in tarot, the I Ching, and bibliomancy. Its use in politics is very old, as office holders in Ancient Athens were chosen by lot, there being no voting.
Other articles related to "random":
... If is a UI random variable, by splitting and bounding each of the two, it can be seen that a uniformly integrable random variable is always bounded in ... It can also be shown that any random variable will satisfy clause 2 in Definition 2 ... If any sequence of random variables is dominated by an integrable, non-negative that is, for all ω and n, then the class of random variables is uniformly ...
... strong, cryptographically secure random passwords ... On Unix platforms /dev/random and /dev/urandom are commonly used, either programmatically or in conjunction with a program such as makepasswd ... Password Generator—describes a standard process for converting random bits (from a hardware random number generator) into somewhat pronounceable "words" suitable for a passphrase ...
... Series, Part 1 Prices" in which he suggested that the movement of shares on the stock market was random i.e ... This ultimately led to the creation of the Random Walk Hypothesis, and the closely related efficient-market hypothesis which states that random price movements indicate a well-fun ...
... of the Vanguard Press for 36 years when, in October 1988, the company was sold to Random House ... of the Vanguard Press was merged into that of Random House, although for 10 years they were to be identified on the title page as Vanguard Press books ... "Random House will take good care of our books and authors," Shrifte said ...
... A random permutation is a random ordering of a set of objects, that is, a permutation-valued random variable ... The use of random permutations is often fundamental to fields that use randomized algorithms such as coding theory, cryptography, and simulation ... A good example of a random permutation is the shuffling of a deck of cards this is ideally a random permutation of the 52 cards ...
Famous quotes containing the word random:
“We should stop looking to law to provide the final answer.... Law cannot save us from ourselves.... We have to go out and try to accomplish our goals and resolve disagreements by doing what we think is right. That energy and resourcefulness, not millions of legal cubicles, is what was great about America. Let judgment and personal conviction be important again.”
—Philip K. Howard, U.S. lawyer. The Death of Common Sense: How Law Is Suffocating America, pp. 186-87, Random House (1994)
“Assemble, first, all casual bits and scraps
That may shake down into a world perhaps;
People this world, by chance created so,
With random persons whom you do not know”
—Robert Graves (18951985)
“It is a secret from nobody that the famous random event is most likely to arise from those parts of the world where the old adage There is no alternative to victory retains a high degree of plausibility.”
—Hannah Arendt (19061975)