Correlation coefficient tells you:

How effective are different psychotherapies? A large-scale study compared the effectiveness of four major forms of therapy in the treatment of anxiety with a fifth control condition: psychodynamic; humanistic; cognitive; behavior; no treatment (control condition). Volunteer patients were assigned by the investigator to one of the five conditions. The anxiety level of each patient after 6 months was measured, using an evaluation scale that measures anxiety level on a 100-point scale. What statistical analysis would you use?

In a study among college students, participants (ages 18-28 years old) completed a self-report questionnaire about their self-esteem. What statistical analysis would you use to see if there was a relationship between the two variables listed?

As part of a study of driver safety, an investigator wants to know the effect of blood-alcohol level on the length of time it takes for a driver's foot to reach the brake pedal following the sudden appearance of an object 50 meters in front of the car. Using a simulator that mimics this driving condition, the investigator measures this reaction time (in seconds) for volunteers under five different conditions: after consuming either 0, 0.5, 1.0, 1.5, 2.0, or 2.5 ounces of alcohol, administered as pure (tasteless) alcohol mixed with orange juice so that, apart from the effects of the alcohol, the volunteers are unaware of which condition they are in. What statistical analysis would you use?