为密度函数的连续型概率分布称之为具有自由度为n的t——分布(或Student分布)。它在数理统计中占有十分重要的地位。几乎所有的的概率与数理统计教科书中都指出t——分布具有下面的重要性质:当自由度n无限增大时,以n为自由度的t——分布趋近于标准正态分布N(0,1),即定理: A continuous probability distribution that is a density function is called t-distribution (or Student distribution) with degrees of freedom n. It occupies a very important position in mathematical statistics. Almost all probability and mathematical statistics textbooks have pointed out that t-distribution has the following important properties: When the degree of freedom n increases infinitely, the distribution of t with n as the degree of freedom approaches the standard normal distribution N ( 0,1), theorem: