The Quinnipiac University Poll conducts nationwide surveys as a public service and for research. This problem is based on the results of one such poll. Independent simple random samples of registered Democrats, Republicans, and Independents were asked, “Do you think the United States economy is in a recession now?” Of the 628 Democrats sampled, 220 responded “yes,” as did 349 of the 471 Republicans sampled and 342 of the 646 Independents sampled. At the 1% significance level, do the data provide sufficient evidence to conclude that a difference exists in the percentages of registered Democrats, Republicans, and Independents who thought the U.S. economy was in a recession at the time?
> What two plots did we use in this chapter to decide whether we can reasonably presume that the assumptions for regression inferences are met by two variables of a population? What properties should those plots have?
> From the website Golf.com, part of Sports Illustrated Sites, we obtained the scores for the first and second rounds of the 2013 U.S. Open golf tournament. You will find those scores on the WeissStats site. - For the estimations and predictions, use a fir
> Suppose that x and y are two variables of a population and that the assumptions for regression inferences are met with x as the predictor variable and y as the response variable. a. What statistic is used to estimate the slope of the population regressio
> The National Oceanic and Atmospheric Administration publishes temperature and precipitation information for cities around the world in Climates of the World. Data on average high temperature (in degrees Fahrenheit) in July and average precipitation (in i
> We have presented some quantitative data sets and specified a grouping method for practicing the concepts. For each data set, a. determine a frequency distribution. b. obtain a relative-frequency distribution. c. construct a frequency histogram based on
> From the International Data Base, published by the U.S. Census Bureau, we obtained data on infant mortality rate (IMR) and life expectancy (LE), in years, for a sample of 60 countries. The data are presented on the WeissStats site. - For the estimations
> Refer to Problem 11. At the 2.5% significance level, do the data provide sufficient evidence to conclude that the variables student-to-faculty ratio and graduation rate are positively linearly correlated? Data from Problem 11: Graduation rate—the percen
> Refer to Problems 11 and 12. a. Find the predicted graduation rate for a university that has a student-to-faculty ratio of 17. b. Find a 95% prediction interval for the graduation rate of a university that has a student-to faculty ratio of 17. c. Explain
> Refer to Problems 11 and 12. a. Find a point estimate for the mean graduation rate of all universities that have a student-to faculty ratio of 17. b. Determine a 95% confidence interval for the mean graduation rate of all universities that have a student
> Refer to Problems 11 and 12. a. At the 5% significance level, do the data provide sufficient evidence to conclude that student to-faculty ratio is useful as a predictor of graduation rate? b. Determine a 95% confidence interval for the slope, β1, of the
> Refer to Problems 11 and 12. Perform a residual analysis to decide whether considering the assumptions for regression inferences to be met by the variables student-to-faculty ratio and graduation rate is reasonable. Data from Problem 12: Refer to Proble
> Refer to Problem 11. a. Determine the regression equation for the data. b. Compute and interpret the standard error of the estimate. c. Presuming that the assumptions for regression inferences are met, interpret your answer to part (b). Data from Proble
> Graduation rate—the percentage of entering freshmen attending full time and graduating within 5 years— and what influences it is a concern in U.S. colleges and universities. U.S. News and World Report’s “College Guide” provides data on graduation rates f
> Identify the relationship between two variables and the terminology used to describe that relationship if a. ρ > 0. b. ρ = 0. c. ρ < 0.
> Suppose that x and y are two variables of a population with x a predictor variable and y a response variable. a. The distribution of all possible values of the response variable y corresponding to a particular value of the predictor variable x is called
> We have presented some quantitative data sets and specified a grouping method for practicing the concepts. For each data set, a. determine a frequency distribution. b. obtain a relative-frequency distribution. c. construct a frequency histogram based on
> Consider an F-curve with d f = (2, 14). Identify the degrees of freedom for the denominator.
> Consider an F-curve with d f = (2, 14). Identify the degrees of freedom for the numerator.
> For a one-way ANOVA, a. identify one purpose of one-way ANOVA tables. b. construct a generic one-way ANOVA table.
> In one-way ANOVA, a. list and interpret the three sums of squares. b. state the one-way ANOVA identity and interpret its meaning with regard to partitioning the total variation among all the data.
> In one-way ANOVA, identify a statistic that measures a. the variation among the sample means. b. the variation within the samples.
> Suppose that you want to compare the means of three populations by using one-way ANOVA. If the sample sizes are 5, 6, and 6, determine the degrees of freedom for the appropriate F-curve.
> On what distribution does one-way ANOVA rely?
> The U.S. Census Bureau collects information on incomes of employed persons and publishes the results in Historical Income Tables. Independent simple random samples of 100 employed persons in each of four age groups gave the data on annual income, in thou
> Another characteristic compared in the hip bone density study discussed in Problem 19 was Maximum Nottingham leg power, in watts. On the WeissStats site, we provide the leg-power data for the three groups, based on the results obtained by the researchers
> State the four assumptions for one-way ANOVA, and explain howthose assumptions can be checked.
> We have presented some quantitative data sets and specified a grouping method for practicing the concepts. For each data set, a. determine a frequency distribution. b. obtain a relative-frequency distribution. c. construct a frequency histogram based on
> In the paper “Voluntary Weight Reduction in Older Men Increases Hip Bone Loss: The Osteoporotic Fractures in Men Study” (Journal of Clinical Endocrinology & Metabolism, Vol. 90, Issue 4, pp. 1998–2004), K. Ensrud et al. reported on the effect of voluntar
> Smoking during pregnancy is hazardous to both the mother and baby. Passive smoking, or inhalation of second-hand smoke, is also a concern. In the article “Detection of Cotinine in Neonate Meconium as a Marker for Nicotine Exposure in Utero” (Eastern Medi
> Genu valgum, commonly known as “knee-knock,” is a condition in which the knees angle in and touch one another when standing. Genu varum, commonly known as “bow-legged,” is a condition in which the knees angle out and the legs bow when standing. In the ar
> Refer to Problem 14. At the 5% significance level, do the data provide sufficient evidence to conclude that a difference in mean losses exists among the three types of robberies? Use one-way ANOVA to perform the required hypothesis test. Data from Probl
> Refer to Problem 14. a. Obtain individual normal probability plots and the standard deviations of the samples. b. Perform a residual analysis. c. Decide whether presuming that the assumptions of normal populations and equal standard deviations are met is
> The Federal Bureau of Investigation conducts surveys to obtain information on the value of losses from various types of robberies. Results of the surveys are published in Population-at-Risk Rates and Selected Crime Indicators. Independent simple random s
> Consider the following hypothetical samples. a. Obtain the sample mean and sample variance of each of the three samples. b. Obtain SST, SSTR, and SSE by using the defining formulas and verify that the one-way ANOVA identity holds. c. Obtain SST, SSTR, an
> Consider an F-curve with d f = (2, 14). Find the F-value with area 0.05 to its right.
> Consider an F-curve with d f = (2, 14). Find the F-value with area 0.01 to its right.
> Consider an F-curve with d f = (2, 14). Determine F0.05.
> We have presented some quantitative data sets and specified a grouping method for practicing the concepts. For each data set, a. determine a frequency distribution. b. obtain a relative-frequency distribution. c. construct a frequency histogram based on
> For what is one-way ANOVA used?
> Suppose that you have bivariate data for a sample of a population. a. How would you decide whether an association exists between the two variables under consideration? b. Assuming that you make no calculation mistakes, could your conclusion be in error?
> Suppose that you have bivariate data for an entire population. a. How would you decide whether an association exists between the two variables under consideration? b. Assuming that you make no calculation mistakes, could your conclusion be in error? Expl
> The U.S. Census Bureau collects information on the U.S. population by ancestry and region of residence and publishes the results in American Community Survey. According to that document, 18% of the population resides in the Northeast. a. If ancestry and
> Regarding the expected-frequency assumptions for a chi-square goodness-of-fit test, a chi-square independence test, or a chi-square homogeneity test, a. state them. b. how important are they?
> If the observed and expected frequencies for a chi-square goodness-of-fit test, a chi-square independence test, or a chi-square homogeneity test matched perfectly, what would be the value of the test statistic?
> Explain why a chi-square goodness-of-fit test, a chi-square independence test, or a chi-square homogeneity test is always right tailed.
> Recall that the number of degrees of freedom for the t-distribution used in a one-mean t-test depends on the sample size. Is that true for the chi-square distribution used in a chi-square a. goodness-of-fit test? b. independence test? c. homogeneity test
> Several years ago, a poll by Gallup asked 1528 adults the following question: “The New Jersey Supreme Court recently ruled that all life-sustaining medical treatment may be withheld or withdrawn from terminally ill patients, provided that is what the pat
> The document Arizona Residential Property Valuation System, published by the Arizona Department of Revenue, describes how county assessors use computerized systems to value single-family residential properties for property tax purposes. On the WeissStats
> We have presented some quantitative data sets and specified a grouping method for practicing the concepts. For each data set, a. determine a frequency distribution. b. obtain a relative-frequency distribution. c. construct a frequency histogram based on
> The U.S. Census Bureau compiles information on money income of people by type of residence and publishes its finding in Current Population Reports. Independent simple random samples of people residing inside principal cities (IPC), outside principal citi
> Regarding a χ2-curve: a. At what point on the horizontal axis does the curve begin? b. Classify its shape as symmetric, left skewed, or right skewed. c. As the number of degrees of freedom increases, a χ2-curve begins to look like another type of curve.
> In the article “Happier and Less Isolated: Internet Use in Old Age” (Journal of Poverty & Social Justice, Vol. 21, Issue 1, pp. 33–45), researcher O. Lelkes explores the impact of Internet use. The following problem is based on the article. A random samp
> Refer to Problems 15–17. a. What percentage of hospitals are under proprietary control? b. What percentage of psychiatric hospitals are under proprietary control? c. What percentage of hospitals are psychiatric hospitals? d. What percentage of hospitals
> Refer to Problems 15 and 16. a. In view of your answer to Problem 16(b), without doing any further calculations, respond true or false to the following statement and explain your answer: “The conditional distributions of facility type within control type
> Refer to Problem 15. a. Obtain the conditional distribution of control type within each facility type. b. Does an association exist between facility type and control type? Explain your answer. c. Find the marginal distribution of control type. d. Constru
> From data in Hospital Statistics, published by the American Hospital Association, we obtained the following contingency table for U.S. hospitals and nursing homes by type of facility and type of control. We used the abbreviations Gov for Government, Prop
> Refer to Problem 12. a. Find the conditional distributions of birth region by party and the marginal distribution of birth region. b. Does an association exist between the variables “birth region” and “party” for the U.S. presidents? Explain your answer.
> Refer to Problem 12. a. Find the conditional distributions of party by birth region and the marginal distribution of party. b. Does an association exist between the variables “birth region” and “party” for the U.S. presidents? Explain your answer. c. Wha
> We have presented some quantitative data sets and specified a grouping method for practicing the concepts. For each data set, a. determine a frequency distribution. b. obtain a relative-frequency distribution. c. construct a frequency histogram based on
> In its Summer 2013 Animal Action Report, the National Anti-Vivisection Society stated that “59% of Americans between the ages of 18 and 29 oppose medical testing on animals.” The percentage of 59% was computed from sample data. a. Identify the population
> From the Information Please Almanac, we compiled the following table on U.S. region of birth and political party of the first 44 U.S. presidents. The table uses these abbreviations: F = Federalist, DR = Democratic-Republican, D = Democratic, W = Whig, R
> The U.S. Census Bureau compiles census data on educational attainment of Americans. From the document Current Population Survey, we obtained the 2010 distribution of educational attainment for U.S. adults 25 years old and older. Here is that distribution
> Consider a χ2-curve with 17 degrees of freedom. Use Table V to determine a. χ20.10. b. χ20.01. c. the χ2-value that has area 0.05 to its right.
> How do you distinguish among the infinitely many different chi-square distributions and their corresponding χ2-curves?
> The National Association of Colleges and Employers sponsors the Graduating Student and Alumni Survey. Part of the survey gauges student optimism in landing a job after graduation. According to one year’s survey results, published in American Demographics
> ABCNEWS.com published the results of a poll that asked U.S. adults whether they would get a smallpox shot if it were available. Sampling, data collection, and tabulation were done by TNS Intersearch of Horsham, Pennsylvania. When the risk of the vaccine
> Suppose that you are using independent samples to compare two population proportions. Fill in the blanks. a. The mean of all possible differences between the two sample proportions equals the . b. For large samples, the possible differences between the t
> A poll was conducted by Opinion Research Corporation to estimate the proportions of men and women who get the “holiday blues.” Identify the a. specified attribute. b. two populations. c. two population proportions. d. two sample proportions. e. According
> What does the margin of error for the estimate of a population proportion tell you?
> Fill in the blanks. a. The mean of all possible sample proportions is equal to the ___? b. For large samples, the possible sample proportions have approximately a distribution. c. A rule of thumb for using a normal distribution to approximate the distrib
> We have presented some quantitative data sets and specified a grouping method for practicing the concepts. For each data set, a. determine a frequency distribution. b. obtain a relative-frequency distribution. c. construct a frequency histogram based on
> Explain what each phrase means in the context of inferences for a population proportion. a. Number of successes b. Number of failures
> Why is a sample proportion generally used to estimate a population proportion instead of obtaining the population proportion directly?
> In the New York Times article “A Common Police Vest Fails the Bulletproof Test,” E. Lichtblau reported on a U.S. Department of Justice study of 103 bulletproof vests containing a fiber known as Zylon. In ballistics tests, only 4 of these vests produced a
> Refer to Problem 13. a. Find a 99% confidence interval for the difference, p1 − p2, between the proportions of men and women smartphone owners. b. Interpret your answer in part (a) in terms of the difference in percentages of men and women smartphone own
> The Pew Internet & American Life Project conducted a survey of smartphone ownership. One aspect of the study involved the gender of smartphone owners. Of 1029 sampled men, 607 owned a smartphone; and of 1223 sampled women, 648 owned a smartphone. At the
> In the article “Height and Weight at Various Ages and Risk of Breast Cancer” (Annals of Epidemiology, Vol. 2, pp. 597–609), L. Brinton and C. Swanson discussed the relationship between height and breast cancer. The study, sponsored by the National Cancer
> In an issue of Parade Magazine, the editors reported on a national survey on law and order. One question asked of the 2512 U.S. adults who took part was whether they believed that juries “almost always” convict the guilty and free the innocent. Only 578
> Refer to Problem 9. a. Determine a sample size that will ensure a margin of error of at most 0.02 for a 95% confidence interval without making a guess for the observed value of p^. b. Find a 95% confidence interval for p if, for a sample of the size dete
> An international poll of physicians was conducted on the New England Journal of Medicine website asking “Do you believe that the overall medicinal benefits of marijuana outweigh the risks and potential harms?” Identify the: a. specified attribute. b. pop
> Find a 98% confidence interval for the difference between the mean litter sizes of cottonmouths in Florida and Virginia. Interpret your result.
> We have presented some quantitative data sets and specified a grouping method for practicing the concepts. For each data set, a. determine a frequency distribution. b. obtain a relative-frequency distribution. c. construct a frequency histogram based on
> In the article “The Eastern Cottonmouth (Agkistrodon piscivorus) at the Northern Edge of Its Range” (Journal of Herpetology, Vol. 29, No. 3, pp. 391–398), C. Blem and L. Blem examined the reproductive characteristics of the eastern cottonmouth. The data
> Refer to Problem 6. Determine a 90% confidence interval for the difference between the mean right-leg strengths of males and females. Interpret your result. Data from Problem 6: In the paper, “Sex Differences in Static Strength and Fatigability in Three
> In the paper, “Sex Differences in Static Strength and Fatigability in Three Different Muscle Groups” (Reasearch Quarterly for Exercise and Sport, Vol. 61(3), pp. 238–242), J. Misner et al. published results of a study on grip and leg strength of males an
> Explain one possible advantage of using a paired sample instead of independent samples.
> Suppose that the variable under consideration is normally distributed on each of the two populations and that you are going to use independent simple random samples to compare the population means. Fill in the blank and explain your answer: Unless you ar
> Regarding the pooled and nonpooled t-procedures, a. what is the difference in assumptions between the two procedures? b. how important is the assumption of independent simple random samples for these procedures? c. how important is the normality assumpti
> The Bureau of Labor Statistics publishes data on weekly earnings of full-time wage and salary workers in Employment and Earnings. Male and female workers were paired according to occupation and experience. Their weekly earnings, in dollars, are provided
> Discuss the basic strategy for comparing the means of two populations based on a simple random paired sample.
> I. Ertugrul et al. conducted a study to determine the association between insulin growth factor 1 (IGF-1) and bone mineral density (BMD) in men over 65 years of age. The researchers published their results in the paper “Relationship Between Insulin-Like
> In the paper, “Drink and Be Merry? Gender, Life Satisfaction, and Alcohol Consumption Among College Students” (Psychology of Addictive Behaviors, Vol. 19, Issue 2, pp. 184–191), J. Murphy et al. examined the impact of alcohol use and alcohol-related prob
> We have presented some quantitative data sets and specified a grouping method for practicing the concepts. For each data set, a. determine a frequency distribution. b. obtain a relative-frequency distribution. c. construct a frequency histogram based on
> For independent samples, the graphs are for the two samples; for a paired sample, the graphs are for the paired differences. The intent is to employ the sample data to perform a hypothesis test to compare the means of the two populations from which the d
> For independent samples, the graphs are for the two samples; for a paired sample, the graphs are for the paired differences. The intent is to employ the sample data to perform a hypothesis test to compare the means of the two populations from which the d
> For independent samples, the graphs are for the two samples; for a paired sample, the graphs are for the paired differences. The intent is to employ the sample data to perform a hypothesis test to compare the means of the two populations from which the d
> For independent samples, the graphs are for the two samples; for a paired sample, the graphs are for the paired differences. The intent is to employ the sample data to perform a hypothesis test to compare the means of the two populations from which the d
> For independent samples, the graphs are for the two samples; for a paired sample, the graphs are for the paired differences. The intent is to employ the sample data to perform a hypothesis test to compare the means of the two populations from which the d
> For independent samples, the graphs are for the two samples; for a paired sample, the graphs are for the paired differences. The intent is to employ the sample data to perform a hypothesis test to compare the means of the two populations from which the d
> Find a 90% confidence interval for the difference in the mean lengths of time that ice stays on the two lakes. Interpret your result.
