n one study subjects were randomly assigned to receive either 500 milligrams of vitamin C daily or a placebo, and the number of colds they came down with during a winter season was noted. In the second study people responded to a questionnaire asking about the average number of hours they sleep per night and the number of colds they came down with during a winter season. a. The first study was an observational study, while the second was a controlled experiment. b. The first study was a controlled experiment, while the second was an observational study. c. Both studies were controlled experiments. d. Both studies were observational studies.

n one study subjects were randomly assigned to receive either 500 milligrams of vitamin C daily or a placebo, and the number of colds they came down with during a winter season was noted. In the second study people responded to a questionnaire asking about the average number of hours they sleep per night and the number of colds they came down with during a winter season. a. The first study was an observational study, while the second was a controlled experiment. b. The first study was a controlled experiment, while the second was an observational study. c. Both studies were controlled experiments. d. Both studies were observational studies.

Holt Mcdougal Larson Pre-algebra: Student Edition 2012

1st Edition

ISBN:9780547587776

Author:HOLT MCDOUGAL

Publisher:HOLT MCDOUGAL

Chapter11: Data Analysis And Probability

Section: Chapter Questions

Problem 8CR

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Question

In one study subjects were randomly assigned to receive either 500 milligrams of vitamin C daily or a placebo, and the number of colds they came down with during a winter season was noted. In the second study people responded to a questionnaire asking about the average number of hours they sleep per night and the number of colds they came down with during a winter season.

	a.	The first study was an observational study, while the second was a controlled experiment.
	b.	The first study was a controlled experiment, while the second was an observational study.
	c.	Both studies were controlled experiments.
	d.	Both studies were observational studies.