数理统计中的“自由度”及教材中一处证明的订正

The Free Degree in Mathematical Statistics and the Improvement of the Certain Certification in the Teaching Material

利用线性代数中二次型矩阵的有关知识,重新定义数理统计中的“自由度”,并对教材中 的证明进行订正.

Redefine the free degree of Mathematical Statistics and improve the certification of in the second line from the bottom on page 377 of the teaching material by making use of the knowledge concerning quadratic type and matrix in linear algebra.