Let 
. A value 
such that 
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, 
, 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
as "not significant,"
, as "significant"
(sometimes denoted *), and 
as "highly significant" (sometimes
denoted **). Some authors use the term "almost significant" to refer to
, although this
practice is not recommended.
