Data scientists want to know if listening to music or podcasts reduce symptoms of stress in individuals. They conducted a study of 1,000 people who were brought into a laboratory office for testing. While wearing a heart-rate monitor, participants were asked to listen to either music or a podcast of their choosing while completing a series of complicated puzzles. The data scientists discovered that on average, participants who listened to music had a 5% lower heart rate while completing the tasks than those who listened topodcasts.
Before publishing their findings, the data scientists have asked you to review their claim. In the space below, indicate possible threats to validity faced by this study.
These materials were developed partly through support of the National Science Foundation,
(awards 1042210, 1535276, 1648684, and 1738598). 
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