Professor Johnston Has Found a Strong Positive Correlation Between Wearing

Multiple Choice

Professor Johnston has found a strong positive correlation between wearing neckties and the frequency of strokes (r = 0.89) .He thinks that the necktie reduces blood flow to the brain,preventing the brain from receiving enough oxygen.Professor Johnston and his associates claim to have proven that wearing neckties causes strokes.What error has Professor Johnston made?

A) An r = 0.89 is not a very large r-value.
B) Professor Johnston is drawing a causal conclusion from correlational findings.
C) Not everyone who wears a necktie wears it very tight.
D) Professor Johnston should know that there are other ways for blood to reach the brain.