What is the minimum value of cor

What is the minimum value of correlation coefficient to prove the existence of the accepted relationship between scores of two of more tests?

Dear Ahmad, unfortunately the interpretation of correlation values usually disregard completely the influence of sample size, and like in statistical significance, size matters. Regarding correlation In Statistics for business and economics, 5e ( 2003) Newbold, P., Carlson, W. L., & Thorne, B. M. (2003) suggested the the threshold r>=2/sqrt( n) as the limit of r indicating a linear relationship. I suggest you to read the work entitled "Correlation Coefficient Rule of Thumb" by Timothy C. Krehbiel, where you can find the statistical justification for such threshold