学生氏分布(t 分布):在生产或科研的实际工作中,为了节省人力、物力和时间、往往不采用大样本而采用小样本,也就是抽样数小于30的样本,甚至取几个抽样组成一个样本来推断总体。这时,就不能采用前述的大样本的推断方法来估计总体了。对大样本,可用样本的均方根差来代替总体的均方根差。但对小样本来 Student’s distribution (t distribution): In the actual work of production or scientific research, in order to save manpower, material resources, and time, a small sample is often used instead of a large sample, that is, a sample with a sampling number of less than 30, even taking several samples. A sample to infer overall. At this time, we cannot use the large sample inference method described above to estimate the population. For large samples, the root mean square error of the population can be replaced by the root mean square error of the sample. But for small samples