Question

1. Common colds are typically caused by a rhinovirus. In a test of effectiveness of Echinacea, some test subjects were treated with Echinacea extracted with 20% ethanol, some were treated with Echinacea extracted with 60% ethanol, and others were given a placebo. All of the test subjects were then exposed to rhinovirus. Results are summarized in Table given below. Use a 0.05 significance level to test the claim that getting an infection (cold) is independent of the treatment group. What does the result indicate about the effectiveness of Echinacea as a treatment for colds? Given that he critical value of c² for 1d.f. = 3.841, the critical value of c² for 2d.f. = 5.991, the critical value of c² for 3d.f. = 7.815.

	Treatment Group			Total
	Placebo	Echinacea:20%extract	Echinacea:60%extract
Infected	85	45	40	170
Not Infected	15	5	10	30
Total	100	50	50	200

2. What is the statistical hypothesis? Define the following terms with reference to testing of a hypothesis-

1. Null and Alternative Hypothesis
2. Critical Region
3. Significance Level
4. Types of Hypothesis Tests
5. Two types of Errors in Hypothesis Tests

Answer 1