Abstract
The analysis of correlation is often used as the statistical method for the research of physical therapy. However, it is sometimes found to be applied inappropriately, and there are some researches that needs more accurate and sufficient discussion substantiated by careful examination and presumption. The necessary conditions for the analysis of correlation are described here; what state of relation is called "correlation", what are correlation coefficient 'r' and regression curve, and what are the rules for obtaining them. For further information, the minimum involution method is also introduced.
