Let delta=z>=z_(observed). A value 0<=alpha<=1 such that P(delta)<=alpha is considered "significant" (i.e., is not simply due to chance) is known as an alpha value. The probability that a variate would assume a value greater than or equal to the observed value strictly by chance, P(delta), is known as a P-value.

Depending on the type of data and conventional practices of a given field of study, a variety of different alpha values may be used. One commonly used terminology takes P(delta)>=5% as "not significant," 1%<P(delta)<5%, as "significant" (sometimes denoted *), and P(delta)<1% as "highly significant" (sometimes denoted **). Some authors use the term "almost significant" to refer to 5%<P(delta)<10%, although this practice is not recommended.

See also

Alpha Value, Coincidence, Confidence Interval, P-Value, Probable Error, Significance Arithmetic, Significance Test, Statistical Test

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Cite this as:

Weisstein, Eric W. "Significance." From MathWorld--A Wolfram Web Resource.

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