请输入您要查询的百科知识:

 

词条 Elementary event
释义

  1. Probability of an elementary event

  2. See also

  3. References

{{redirect2|Basic outcome | Atomic event|atomic events in computer science|linearizability}}{{Probability fundamentals}}

In probability theory, an elementary event (also called an atomic event or simple event) is an event which contains only a single outcome in the sample space.[1] Using set theory terminology, an elementary event is a singleton. Elementary events and their corresponding outcomes are often written interchangeably for simplicity, as such an event corresponds to precisely one outcome.

The following are examples of elementary events:

  • All sets {k}, where k ∈ N if objects are being counted and the sample space is S = {0, 1, 2, 3, ...} (the natural numbers).
  • {HH}, {HT}, {TH} and {TT} if a coin is tossed twice. S = {HH, HT, TH, TT}. H stands for heads and T for tails.
  • All sets {x}, where x is a real number. Here X is a random variable with a normal distribution and S = (−∞, +∞). This example shows that, because the probability of each elementary event is zero, the probabilities assigned to elementary events do not determine a continuous probability distribution.

Probability of an elementary event

Elementary events may occur with probabilities that are between zero and one (inclusively). In a discrete probability distribution whose sample space is finite, each elementary event is assigned a particular probability. In contrast, in a continuous distribution, individual elementary events must all have a probability of zero because there are infinitely many of them— then non-zero probabilities can only be assigned to non-elementary events.

Some "mixed" distributions contain both stretches of continuous elementary events and some discrete elementary events; the discrete elementary events in such distributions can be called atoms or atomic events and can have non-zero probabilities.[2]

Under the measure-theoretic definition of a probability space, the probability of an elementary event need not even be defined. In particular, the set of events on which probability is defined may be some σ-algebra on S and not necessarily the full power set.

See also

  • Atom (measure theory)

References

1. ^{{cite book | last = Wackerly | first = Denniss |author2=William Mendenhall |author3=Richard Scheaffer | title = Mathematical Statistics with Applications | publisher = Duxbury | isbn = 0-534-37741-6}}
2. ^{{cite book | last = Kallenberg | first = Olav | title = Foundations of Modern Probability | edition = 2nd | year = 2002 | page = 9 | url = https://books.google.com/books/about/Foundations_of_Modern_Probability.html?id=L6fhXh13OyMC | publisher = Springer | location = New York | isbn = 0-387-94957-7}}
  • Pfeiffer, Paul E. (1978) Concepts of probability theory. Dover Publications. {{ISBN|978-0-486-63677-1}} ({{Google books|_mayRBczVRwC|online copy|page=18|}})
{{probability-stub}}{{statistics-stub}}

1 : Experiment (probability theory)

随便看

 

开放百科全书收录14589846条英语、德语、日语等多语种百科知识,基本涵盖了大多数领域的百科知识,是一部内容自由、开放的电子版国际百科全书。

 

Copyright © 2023 OENC.NET All Rights Reserved
京ICP备2021023879号 更新时间:2024/9/23 21:23:51