摘要：The author calculated the mean and standard deviation of 35 estimated values of water gathered from many rivers, and compared them with those of well water. The correlation coefficient among 22 estimated values obtained from river water was calculated by using 178 sheets of correlation charts. The equation of regression line were presented for the strongly correlated groups, by use of which one can estimate a value from another strongly correlated one. The picture of regression lines were also given. About BOD, multiple correlation and regression plane were analysed.
