Scenario: A professor wants to examine whether being an athlete is associated with retention at their college. She finds that the research is contradictory - some research suggests it may improve retention but other research suggests it has no effect. She operationally defines athletic status as YES or NO, and retention as a self-report question (scale of 0 - 100% likelihood of coming back the next term).

What is the null hypothesis in this scenario (use a complete sentence)? Is it one- or two-tailed?

What type of correlational analysis is most appropriate and why?