The interpretation of a correlation coefficient depends on the context and purposes. A correlation of 0.8 may be very low if one is verifying a physical or chemical law , but may be regarded as very high in the social sciences where there may be a greater contribution from complicating factors. Also, whether a coefficient is considered significant can be assessed by comparing the value obtained to that expected by the null hypothesis or by deriving a confidence interval that, on repeated sampling, has a given probability of containing the coefficient :)