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a. What is the probability that a customer does not use a credit card? b. What is the probability that a customer pays in cash or with a credit card? What is the standard error of the mean for each group? Pulmonary Disease The data in Table 6.10 concern the mean triceps skin-fold thickness in a group of normal men and a group of men with chronic... Compute a 95% CI for the mean age? Refer to the data in Table 2.13. Regard this hospital as typical of Pennsylvania hospitals. Table 2.13: Hospital-stay data Is there a difference between men and women in their preference for working for some government agency? Conduct a test to determine whether there is enough evidence to infer that women (SEX: 1 =... An article in the Journal of American College Health reports that, in a survey of 1845 college students from a large, southeastern public university, 27% were at risk for at least one sleep disorder,... Restaurants sometimes provide customer reaction cards so that customers can evaluate their dining experience at the establishment. What kinds of decisions might be made on the basis of this... What is the coefficient of determination and what does it tell us about the relationship between two variables? Compute the standard deviation based on the sample of six means. What is another name for this quantity? Table 6.2: Sample of birth-weights (oz) obtained from 1000 consecutive deliveries at Boston... Select the third point from each of the six samples, and compute the sample sd from the collection of six third points? Table 6.2: Sample of birth-weights (oz) obtained from 1000 consecutive... How do the actual sample results in Problems 6.48 and 6.49 compare? Obstetrics Figure 6.4b (p. 172) plotted the sampling distribution of the mean from 200 samples of size 5 from the population of... If the central-limit theorem holds, what proportion of the sample means should fall within 0.5 lb of the population mean (112.0 oz)? Obstetrics Figure 6.4b (p. 172) plotted the sampling distribution... Do you feel the central-limit theorem is applicable for samples of size 5 from this population? Explain. Obstetrics Figure 6.4b (p. 172) plotted the sampling distribution of the mean from 200 samples... Compare your results in Problems 6.52 and 6.53 with the actual proportion of sample means that fall in these ranges? Obstetrics Figure 6.4b (p. 172) plotted the sampling distribution of the mean from... Suppose (x - 0 ) / (s/n) = -1.52 and a one- sample t test is performed based on seven subjects. What is thaw two-tailed p-values? Renal Disease The mean serum-creatinine level measured in 12... What is the p-value for the test conducted in Problem 7.36? Nutrition Iron-deficiency anemia is an important nutritional health problem in the United States. A dietary assessment was performed on 51... Refer to Exercise 22.4. Set up the opportunity loss table. In exercise 22.4 Given the following payoff table, draw the decision tree: -1 4 10 S1 S2 S3 20 -10 If the expected difference is 0.10 ln units, then what is the power of such a study if a two-sided test is to be used with = .05? Diabetes Plasma-glucose levels are used to determine the presence of... An order for an automobile can specify either an automatic or a standard transmission, either with or without air conditioning, and with any one of the four colors red, blue, black, or white.... What test can be used to assess if there is a change in mean LVM over 4 years? Cardiovascular Disease, Pediatrics Left ventricular mass (LVM) is an important risk factor for subsequent cardiovascular... Carry out the test procedure mentioned in Problem 8.28, and report a p-value? Ophthalmology A camera has been developed to detect the presence of cataract more accurately. Using this camera, the gray... What are the appropriate null and alternative hypotheses to compare the means of the two groups? Pulmonary Disease A possible important environmental determinant of lung function in children is the... Provide a 95% CI for the true mean difference in FEV between 5- to 9-year-old children whose parents smoke and comparable children whose parents do not smoke? Pulmonary Disease A possible important... Suppose another investigator wants to reproduce the results of the Amish study. She can recruit 100 subjects with the II genotype and 100 subjects with the ID genotype. How much power will the study... Perform the test in Problem 8.112, and report a p-value (two-tailed)? Microbiology A study sought to demonstrate that soy beans inoculated with nitrogen-fixing bacteria yield more and grow adequately... Suppose there is some overlap between the 95% CIs in Problem 8.110. Does this necessarily imply there is no significant difference between the mean pod weights for the two groups? Why or why not?... Provide a 95% CI for the mean pod weight in each group? Microbiology A study sought to demonstrate that soy beans inoculated with nitrogen-fixing bacteria yield more and grow adequately without the... Use the previous information to answer the following questions about the class survey. a. Describe in words the parameter of interest. b. Identify the numeric value of the statistic corresponding to... Implement the test in Problem 9.47, and report a twotailed p-value? Table 9.15: (Weight change, control period) (weight change, lack-of-consistency period) among 23 adolescent diabetic boys 4, A.... What significance test can be used to assess whether there is a relationship between receiving an antibiotic and receiving a bacterial culture while in the hospital? Refer to Table 2.13 (p. 36).... Are the present diagnosis and prior episodes of urethritis associated? Sexually Transmitted Disease Suppose researchers do an epidemiologic investigation of people entering a sexually transmitted... Provide a point estimate and a 95% confidence interval for the prevalence of otorrhea at 2 weeks in the observation group? Otolaryngology Many children have tympanostomy tubes surgically inserted in... Perform the test in Problem 10.21 and report a p-value (two-tailed). Interpret your results in words? Otolaryngology Many children have tympanostomy tubes surgically inserted in their ears to reduce... Lie detector tests are similar to hypothesis tests in that there are two possible decisions and two possible realities and therefore two kinds of errors that can be made. The hypotheses can be... Based on all matched pairs, how much power did the study just mentioned have vs. the alternative hypothesis that a widower is twice as likely to die before a married person of the same age and... Provide a stem-and-leaf plot of the age at first sperm-positive urine specimen? Pediatrics, Endocrinology A study was performed among 40 boys in a school in Edinburgh to look at the presence of... Suppose we are uncertain whether a normal distribution provides a good fit to the distribution of age at spermatogenesis. Answer this question using the results from Problems 10.4710.49. (Assume that... Was the sample random? Suppose mean age at spermatogenesis = 13.67 years, with standard deviation = 0.89 years and we assume that the age at spermatogenesis follows a normal distribution. The pediatrician would like to... If we assume that all boys have no sperm cells at age 11 (11.0 years) and all have sperm cells at age 18, then estimate the probability of first developing sperm cells at ages 12 (i.e., between 12.0... One assumption of the test in Problem 10.68 is that the distribution of serum retinol is approximately normal. To verify this assumption, the investigators obtained a frequency distribution of serum... Implement the test in Problem 10.74, and report a p-value? Zoology A study was performed to look at the preference of different species of birds for different types of sunflower seeds. Two bird... What test can be performed to study the association between case/control status and risk score? Specifically, we are interested in testing whether cases tend to have consistently higher risk scores... Fit a regression line relating 5-year lung-cancer mortality to annual cigarette consumption when each is expressed in the log 10 scale? Cancer The following statistics are taken from an article by... To test the significance of this regression line, is it necessary to perform any additional tests other than those in Problem 11.20? If so, perform them. Cancer The following statistics are taken... Is this an observational study or an experiment? How are you deciding? The researcher is now interested in seeing whether a higher proportion of men in the group that crossed the Capilano Canyon... Fill in the cells in the following table so there is no association between the explanatory and response variables. Female Total Male Played sports in high school Yes 200 160 No Total 150 210 360 Fill in the cells in the following table so there is no association between the explanatory and response variables. Member of Fraternity or Sorority Yes No Total Yes 152 Has one or more alcoholic... Use ANOVA methods to estimate the CV for plasma beta-carotene for the 23 participants, based on the two baseline measurements? Table 12.35: Format of BETACAR.DAT Code Variable Column Preparation... Approximately what does the box portion of a boxplot display? A. The middle quarter of the data B. The middle half of the data C. The lower quarter of the data D. The upper quarter of the data On a data set that is bell-shaped, which will typically be larger, its standard deviation or its inter-quartile range? Using the candy bar weight data shown in the previous exercise, do the following: a. Find the five-number summary for both sets of candy bar weights. b. Construct parallel boxplots for both sets of... Summarize the findings in a few sentences, and compare them with the results in Problem 12.62? Hypertension Refer to Table 12.16 (on page 595). A similar ANCOVA was performed using PROC GLM of SAS... Perform a significance test to examine the association between OC use and bacteriuria after controlling for age? Refer to Table 13.8. Risk of bacteriuria among OC users and nonusers % with... For each region, assess whether the change in corneal sensitivity varies by treatment received comparing day 7 vs. day 0 and day 14 vs. day 0, respectively. Use all available data from all 93... Estimate the odds ratio for Group C vs. Group A and provide a 95% CI. Are the results consistent with those in Problem 13.21? Why or why not? One assumption in Table 13.46 is that the log odds ratio... What do these statistical tests mean in this instance? Cardiovascular Disease Sudden death is an important, lethal cardiovascular endpoint. Most previous studies of risk factors for sudden death have... Reconsider the previous exercise about haircut prices. The p-value for the appropriate test turns out to be 0.0022. What would you conclude? (Circle all that apply.) A. The sample data provide strong... Provide a 95% CI for the OR? Table 13.27 Use of SAS PROC PHREG to perform conditional logistic regression on the breast cancer data One assumption in Table 13.46 is that the log odds ratio of being a... Assess whether there are any significant treatment or carry-over effects of SBP or DBP in study 1? Three separate two-period cross-over studies were performed, based on different groups of subjects.... What is the difference between paired design using repeated measures and paired design using matching? Is there a significant association between MI and severe vertex baldness after controlling for age? Please report a two-tailed p-value. Cardiovascular Disease A study was performed relating baldness... Suppose that you want to determine whether there is a difference between the distances traveled by two different brands of golf balls. You use the 30 people on your golf league to participate in the... Estimate the OR between widowhood and mortality, and provide a 95% CI about this estimate? Mental Health Refer to Table 10.27. Table 13.27 Use of SAS PROC PHREG to perform conditional logistic... Match the appropriate test of significance to each of the following research questions. 1. Testing a single proportion 2. Testing a single mean 3. Comparing two proportions 4. Comparing two means... A researcher measures body flexibility in college students. She suspects that females will be more flexible than males. a. State the null and alternative hypotheses. b. Identify the explanatory and... Provide a two-sided 95% CI for incidence rate of flu among high-risk students during winter 20082009? Infectious Disease Suppose the incidence rate of influenza (flu) during the winter of 20082009... Which of the following are true about the MAD statistic? There may be more than one statement that is true. a. The MAD statistic can never be negative. b. The MAD statistic is the average distance... Answer the question posed in Problem 14.69, while accounting for possible age and gender differences between groups? FIELD.DOC Column _________________________________________ Variable 16... Refer to Exercise 6.16. The numbers (in millions) of Americans speaking non-English languages at home are listed next. If one individual is selected at random find the probability of the following... Most televised baseball games display a pitch tracker that shows whether the pitch was in the strike zone, which in turn shows whether the umpire made the correct call. Major League Baseball keeps... Study after study indicate that men earn higher incomes than women (SEX: 1 = Male, 2 = Female). a. To determine the extent of the differential in 2014 estimate the difference between male and female... If you took repeated samples of size 150 and constructed a 99% confidence interval for the population mean of hours slept from each sample, what percentage of these intervals would capture the... Refer to Exercise 17.17 a. Use stepwise regression to compute the regression equation. b. Compare the output with that produced in Exercise 17.17. In exercise 17.17 La Quinta Motor Inns is a... Find the probabilities. 1. P(Z < 1.60) 2. P(Z < 1.61) 3. P(Z < 1.65) 4. P(Z < 1.39) 5. P(Z < 1.80) 6. P(Z < 2.16) 7. P(1.30 < Z < .70) 8. P(Z > 1.24) 9. P(Z < 2.23) 10. P(Z > 1.87) 11. P(Z < 2.57)... The breakdown of U.S. cities having a population of at least 10,000 persons has been reported as follows. a. How many cities have a population of at least 25,000 but less than 500,000? b. How many... Use the One Proportion applet to simulate 1,000 repetitions of this study, assuming that every driver is just as likely to talk on the cell phone as not while driving. Report what values you input... The International Council of Shopping Centers reports that the average teenager spends $39 during a shopping trip to the mall. The promotions director of a local mall has used a variety of strategies... The dotplot generated below by the One Proportion applet assumed the long-run proportion of winning was equal to 50%. Use this dotplot to answer the following questions. a. How many dots are in the... What has to be true about the observed proportions if the MAD statistic is zero? Janine serves 30 short serves with her right hand and gets 17 of the 30 in the court. a. What are two possible explanations for Janine getting 17 out of 30 right-handed short serves in? b. Which of... Summarize the findings from the study. What worked well in this study design? What would you change? What are some follow-up research questions you would like to explore based on the findings from... Are you able to conclude that the association between hand span and number of Tootsie Rolls grabbed is causal? Explain. Is hand span a good predictor of how much candy you can grab? Using 45 college... An international manufacturer of electronic products is contemplating introducing a new type of compact disk player. After some analysis of the market, the president of the company concludes that,... An article in The Journal of Data Science [A Statistical Analysis of Well Failures in Baltimore County (2009, Vol. 7, pp. 111127)] provided the following table of well failures for different... For a given data set, a test of association based on a slope is equivalent to a test of association based on a correlation coefficient. Being equivalent means which of the following is true? A. The... Which of the following does the method of least squares minimize? A. Sum of vertical distances between observations and the line B. Sum of squared vertical distances between observations and the line... Reconsider the previous two exercises about textbook prices. Th e equation of the least squares regression line for predicting price from number of pages is price = 14.11 + 0.13 (pages). a. Interpret... Find a solution of x dy/dx = y 2 - y that passes through the indicated points. (a) (0, 1) (b) (0, 0) (c) (12, ) (d) (2, ) Consider the bar code 39 is a common bar code system that consists of narrow and wide bars (black) separated by either wide or narrow spaces (white). Each character contains nine elements (five bars... In one part of the study, the experimenter approached individual rhesus monkeys and placed two boxes an equal distance from the monkey. The experimenter then placed food in one of the boxes, making... Consider the gain estimation problem in Exercise 8-4. (a) How large must n be if the length of the 95% CI is to be 40? (b) How large must n be if the length of the 99% CI is to be 40? Use the data from Exercise 8-68 to compute a two-sided Agresti-Coull CI on the proportion of seeds that germinate. Compare and discuss the CI to the one computed in Exercise 8-68. a. Identify the parameter of interest for this study and assign a symbol to it. b. If Krieger is just randomly choosing between the two objects, what is the chance that he will choose the correct... Is there evidence to suggest that the standard deviations of the algae concentrations in the two types of rivers (flow rates) in Exercise 10-36 differ? Use = 0.05. Consider a multiple regression model with k regressors. Show that the test statistic for significance of regression can be written as Suppose that n = 20, k = 4, and R 2 = 090. If = 0.05, what... Find the general solution of the given differential equation. Give the largest interval I over which the general solution is defined. Determine whether there are any transient terms in the general... Suppose two brothers named Mario and Luigi like to compete by playing a certain video game. Mario thinks he is better at this game than Luigi and sets out to prove it by keeping track of who wins.... Determine whether the given differential equation is exact. If it is exact, solve it. (2x - 1) dx + (3y + 7) dy = 0 The differential equation dp/dt = (k cost)P, where k is a positive constant, is a model of human population P(t) of a certain community. Discuss an interpretation for the solution of this equation.... Evaluate the strength of evidence for the hypotheses in the previous question. a. Find the p-value for the hypotheses in the previous question using a simulation-based approach. b. Based on the...
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