Abstract: Although the degrees of freedom concept is very important in biostatistics, in many textbooks, there are no clear definitions or adequate explanations of the concept. Consequently, the degrees of freedom concept is too abstract to be grasped by students, as well as being difficult to be explained by teachers. Moreover, the concept is often introduced firstly into biostatistics textbooks at calculating the sample variance. If the concept is expressed more vividly at this time, it will bring students a solid foundation for the follow-up study. In this paper, the VBA programming and graphics function of Excel software are used to simulate the process of random sampling, which can show the connotation of degrees of freedom more vividly and stimulate students′ interests in learning, so as to achieve a good teaching effect.

Key words: sample variance, degrees of freedom, Excel, simulation