SAT and ACT math terms · SAT Math, ACT Math
Observational study vs. experiment
Observational study vs. experiment: An experiment randomly assigns treatments and can show cause and effect; an observational study only observes and can show association.
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What it means
Random assignment to treatment groups is what allows a study to support a causal conclusion. Random selection from a population is what allows results to be generalized to that population.
Without random assignment, a confounding variable could explain an observed association.
Example
Researchers observe that people who drink more coffee sleep less. Without random assignment, they cannot conclude that coffee causes less sleep.
On the exam
The SAT asks which conclusion a study's design supports.