RandomState.standard_t(df, size=None)

Standard Student’s t distribution with df degrees of freedom.

A special case of the hyperbolic distribution. As df gets large, the result resembles that of the standard normal distribution (standard_normal).


df : int

Degrees of freedom, should be > 0.

size : int or tuple of ints, optional

Output shape. Default is None, in which case a single value is returned.


samples : ndarray or scalar

Drawn samples.


The probability density function for the t distribution is

P(x, df) = \frac{\Gamma(\frac{df+1}{2})}{\sqrt{\pi df}
\Gamma(\frac{df}{2})}\Bigl( 1+\frac{x^2}{df} \Bigr)^{-(df+1)/2}

The t test is based on an assumption that the data come from a Normal distribution. The t test provides a way to test whether the sample mean (that is the mean calculated from the data) is a good estimate of the true mean.

The derivation of the t-distribution was forst published in 1908 by William Gisset while working for the Guinness Brewery in Dublin. Due to proprietary issues, he had to publish under a pseudonym, and so he used the name Student.


[R223]Dalgaard, Peter, “Introductory Statistics With R”, Springer, 2002.
[R224]Wikipedia, “Student’s t-distribution”’s_t-distribution


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