Question 41·Medium·Evaluate Statistical Claims: Observational Studies and Experiments

The study can provide an unbiased estimate for all teenagers in the state because the 100 students were chosen at random.

The study can estimate average sleep only for students at the researcher’s high school because the sampling frame was limited to that school.

The study can establish that school workload causes reduced sleep because the researcher controlled the conditions.

The study is invalid because teenagers from outside the state were not surveyed.