correlation and regression

Scattergrams are useful and the value of simple visual inspection is most important in determining a trend between two variables, whether or
not there is a reasonable correlation between them. However, it is better if a more objective and quantitative measure can be used to measure
the degree of correlation. The "correlation coefficient" is a useful measure of correlation and "regression analysis" allows the construction of
a regression equation which can be used to predict future values and rents.

THE CORRELATION COEFFICIENT (r) AND COEFFICIENT OF DETERMINATION (r2)

The purpose of correlation analysis is to analyze the degree of relationship among the values of 2 or more variables.
The measure of correlation between 2 variables can be measured with "r2", the "coefficient of determination":

Perfect positive correlation: r2 = +1
No correlation: r2 = 0
Perfect negative correlation: r2 = -1