t distribution

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t dis·tri·bu·tion

the distribution of the quotient of independent random variables, the numerator of which is a standardized normal variate and the denominator the positive square root of the quotient of a chi-square (χ2) distributed variate and its number of degrees of freedom.

t statistic, t distribution

the statistical distribution of the ratio of the sample mean to its sample standard deviation for a normal random variable with zero mean. It is the basis of various t-tests used to make inferences about the mean of a normal variable.