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In Exercises 1–5, use the following survey results: Randomly selected subjects were asked if they were aware that the Earth has lost half of its wildlife population during the past 50 years. Among 1121 women, 23% said that they were aware. Among 1084 men, 26% said that they were aware (based on data from a Harris poll).

Biodiversity Assume that a P-value of 0.1 is obtained when testing the claim given in Exercise 1 “Biodiversity.” What should be concluded about the null hypothesis? What should be the final conclusion?

Short Answer

Expert verified

The null hypothesis fails to be rejected.

There is insufficient evidence to reject the claim that the proportion of women who were aware of the fact is equal to the proportion of men who were aware of the fact.

Step by step solution

01

Step 1: Given information

In a sample of 1121 women, 23% said that they were aware of the fact that the Earth has lost half of its wildlife population during the past 50 years. In another sample of 1048 men, 26% said that they were aware that the Earth has lost half of its wildlife population during the past 50 years.

It is claimed that the proportion of women who were about the fact is equal to the proportion of men who were aware of the fact.

02

Formulation of the hypotheses

Null hypothesis: The proportion of women who were aware of the factis equal to the proportion of men who were aware of the fact.

\({H_0}\):\({p_1} = {p_2}\).

Alternative hypothesis:The proportion of women who were aware of the factis not equal to the proportion of men who were aware of the fact.

\({H_1}\):\({p_1} \ne {p_2}\)

03

Interpretation of the p-value

The p-value is equal to 0.1.

Let the level of significance be equal to 0.05.

Since the p-value is greater than 0.05, the null hypothesis fails to be rejected.

There is insufficient evidence to reject the claimthat the proportion of women who were aware of the factis equal to the proportion of men who were aware of the fact.

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Most popular questions from this chapter

In Exercises 5–20, assume that the two samples are independent simple random samples selected from normally distributed populations, and do not assume that the population standard deviations are equal. (Note: Answers in Appendix D include technology answers based on Formula 9-1 along with “Table” answers based on Table A-3 with df equal to the smaller of n1−1 and n2−1.)Color and Cognition Researchers from the University of British Columbia conducted a study to investigate the effects of color on cognitive tasks. Words were displayed on a computer screen with background colors of red and blue. Results from scores on a test of word recall are given below. Higher scores correspond to greater word recall.

a. Use a 0.05 significance level to test the claim that the samples are from populations with the same mean.

b. Construct a confidence interval appropriate for the hypothesis test in part (a). What is it about the confidence interval that causes us to reach the same conclusion from part (a)?

c. Does the background color appear to have an effect on word recall scores? If so, which color appears to be associated with higher word memory recall scores?

Red Background n = 35, x = 15.89, s = 5.90

Blue Background n = 36, x = 12.31, s = 5.48

Before/After Treatment Results Captopril is a drug designed to lower systolic blood pressure. When subjects were treated with this drug, their systolic blood pressure readings (in mm Hg) were measured before and after the drug was taken. Results are given in the accompanying table (based on data from “Essential Hypertension: Effect of an Oral Inhibitor of Angiotensin-Converting Enzyme,” by MacGregor et al., British Medical Journal, Vol. 2). Using a 0.01 significance level, is there sufficient evidence to support the claim that captopril is effective in lowering systolic blood pressure?

Subject

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B

C

D

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F

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Before

200

174

198

170

179

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209

185

155

169

210

After

191

170

177

167

159

151

176

183

159

145

146

177

Verifying requirements in the largest clinical trial ever conducted, 401,974 children were randomly assigned to two groups. The treatment group considered of 201,229 children given the sulk vaccine for polio, and 33 of those children developed polio. The other 200,745 children were given a placebo, and 115 of those children developed polio. If we want to use the methods of this section to test the claim that the rate of polio is less for children given the sulk vaccine, are the requirements for a hypothesis test satisfied? Explain.

Braking Reaction Times: Histogram Listed below are sorted braking reaction times (in 1>10,000 sec) for male and female subjects (based on data from the RT-2S Brake Reaction Time Tester). Construct a histogram for the reaction times of males. Use a class width of 8 and use 28 as the lower limit of the first class. For the horizontal axis, use class midpoint values. Does it appear that the data are from a population with a normal distribution?

Males

28

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34

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36

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36

36

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46

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60

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63

Females

22

24

34

36

36

37

39

41

41

43

43

45

45

47

53

54

54

55

56

57

57

57

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80

Denomination Effect In the article “The Denomination Effect” by Priya Raghubir and Joydeep Srivastava, Journal of Consumer Research, Vol. 36, researchers reported results from studies conducted to determine whether people have different spending characteristics when they have larger bills, such as a \(20 bill, instead of smaller bills, such as twenty \)1 bills. In one trial, 89 undergraduate business students from two different colleges were randomly assigned to two different groups. In the “dollar bill” group, 46 subjects were given dollar bills; the “quarter” group consisted of 43 subjects given quarters. All subjects from both groups were given a choice of keeping the money or buying gum or mints. The article includes the claim that “money in a large denomination is less likely to be spent relative to an equivalent amount in smaller denominations.” Test that claim using a 0.05 significance level with the following sample data from the study.

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