The university student sports study manner, the exercise manner, the cordiality performance and the team spirit have the difference in the population statistics variable.
大学生体育学习态度、锻炼态度、情意表现与合作精神在人口统计学变量上存在着差异。
2
The main approach to solve this problem is to stratify the population studied through taking the confounder as the stratifying variable.
解决这一问题的主要方法是将混杂因子作为分层变量把被研究群体分层。
3
Using method of qualitative theory of ordinary differential equation, studies economic harvesting model with variable price and cost for a single population.