Fix It After Reading About the Mozart Effect, Francis Wants to Examine

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After reading about the Mozart effect, Francis wants to examine whether music makes you smarter. He asks 200 people to report how much time they listen to music during a typical week and what their IQ is. He divides the participants into two groups based on their IQ: those with an IQ of less than 100, and those with an IQ of greater than 100. He compares the amount of time each group listens to music using an independent t-test. His results indicate those with an IQ of 100 or more listen to significantly more music than those with an IQ of 100 or less. Francis presents his work at a regional psychology conference. The title of his poster, "Music Makes You Smarter," draws a lot of attention. Many people who talk to Francis about the study say his design cannot infer causality and he analyzed the data incorrectly. What do you think they are referring to? Do you think they are being too hard on him? Fix it!