What defines a strong or weak correlation?
The explanation is given below.
Correlation measures the cause and effect relationship that exists between two variables X and Y.
The possibilities are
As X increases, Y also increases (As X decrease, Y also decreases) - i.e. both variables move in the same direction.
X and Y move in opposite directions. I.e. When X increases, Y decreases and when X decreases, Y increases.
The movement in X or Y has no direct effect on the other variables - i.e. X and Y are independent.
When X and Y are independent, there is zero correlation.
Thus any value near zero, the correlation is weak, if at all.
As correlation increases , the correlation is stronger.