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Problem 19 - Entrance Test

A study found a strong positive correlation between the number of ice cream sales and the number of shark attacks reported in coastal regions over a year. The data showed that as ice cream sales increased, shark attacks also increased. Which of the following is a significant limitation in concluding a direct causal link between ice cream sales and shark attacks from this data alone?

Correct: B

This is a classic example of 'correlation does not imply causation'. While two variables might show a strong statistical relationship (correlation), it does not automatically mean that one causes the other. Often, a third, unmeasured variable (a 'lurking variable') influences both. In this scenario, hot weather (temperature) is a likely lurking variable: hot weather leads to more people buying ice cream and more people swimming in the ocean, which increases the probability of shark encounters. Therefore, concluding a direct causal link without considering other factors is a significant limitation.