A researcher finds a strong positive correlation between average ice cream sales and the rate of swimming pool drownings. She is suspicious of this relationship, but finds the same result across multiple US cities. How would you best advise her?
a. She should calculate a partial correlation to remove the effect of weather/temperature.
b. She should take more samples to be sure her result is accurate.
c. She should calculate r2 to determine if she made an error.
d. She should alert the public to stop buying ice cream.