Common Core: S-IC.3
Problem 18 of 45s12-018
Researchers randomly assign 120 volunteers to drink green tea or water daily for 8 weeks. Blood pressure falls by much more in the tea group. What can they conclude?
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Solution walkthrough1:55
- The researchers decided who drank tea and who drank water. A treatment was imposed, so this is an experiment.
- Random assignment makes the two groups alike on average in age, diet, stress and everything else.
- The only planned difference is the drink, so a much bigger drop in the tea group shows tea caused it.
- If people chose their own drink, it would be observational: tea drinkers may differ, so only a link is shown.
- The volunteers were not a random sample of all adults, so the result applies to people like these volunteers.
- Traps: treatments were imposed (not observational), cause needs random assignment, and volunteers are not all adults.