t-test of a correlation coefficient is used for testing the sample correlation against population correlation of zero. To test an assumed value of the population coefficient other than zero, we should use z-test for a correlation coefficient.


  1. What makes the tests different such that the t-test can only test for zero? Isn't the z-test a special case of the t-test (infinite degree of freedom)?

  2. Since the t-test can't be used for tested for non-zero correlation. Why can't we always use the z-test? What's the point of the t-test?

EDITED for reference:

100 Statistical Tests by Gopal K.Janji

enter image description here


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.