单词	t distribution
释义	t distribution noun : a probability density function that is used especially in testing hypotheses concerning means of normal distributions whose standard deviations are unknown and that is the distribution of a random variable {latex}t = \\frac{u\\sqrt{n}}{v}{/latex} where u and v are themselves independent random variables and u has a normal distribution with mean 0 and a standard deviation of 1 and v2 has a chi-square distribution with n degrees of freedom called also student's t distribution Word History First Known Use circa 1957, in the meaning defined above
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