Perfect Multicollinearity检测方法

        Perfect Multicollinearity检测方法是有两种吗？t-test indicate that none of the individual coefficient is signifacantly different than zero, while the F-test indicates overall significance and the R2 (R方) is high.  这种情形是        Perfect Multicollinearity还是        imerfect Multicollinearity？  如果 相关系数大于0.7则认为是        Perfect Multicollinearity，若相关系数<0.7，但是>0，则认为是        imerfect Multicollinearity，对吗？