The Coefficient of Correlation
is used to express the strength of the relationship
between two variables.
The coefficient of correlation has a value
between -1 and +1. A coefficient of +1 means
perfect positive correlation. A coefficient
of -1 means perfect negative correlation
(when one variable increases the other decreases).
A coefficient close to zero means the variables
are not related. Correlation
is used in Regression
The coefficient of correlation is conventionally
called 'R'. Examples of values of R are:
The formula for R is: