Referenced from lesson Threats to Validity (Spring, 2021)
Data scientists surveyed 100 coffee and tea drinkers over a 1-month period to determine a connection between caffeine consumption and sleep disorders. Respondents were asked questions regarding the amount of coffee or tea consumed daily, dietary habits, sleep habits, and exercise levels. Based on this survey, the data scientists claim that people who drink tea exclusively have moreincidents of insomnia than people who drank coffee exclusively.
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). 
Bootstrap:Data Science by the Bootstrap Community is licensed under a Creative Commons 4.0 Unported License. This license does not grant permission to run training or professional development. Offering training or professional development with materials substantially derived from Bootstrap must be approved in writing by a Bootstrap Director. Permissions beyond the scope of this license, such as to run training, may be available by contacting contact@BootstrapWorld.org.