The degree of clinical agreement among physicians on the presence or absence of generalized lymphadenopathy was assessed in 32 randomly selected participants from a prospective study of male sexual contacts of men with acquired immunodeficiency syndrome (AIDS) or an AIDS-related condition (ARC) [8]. The total number of palpable lymph nodes was assessed by each of three physicians. Results from two of the three physicians are presented in Table 8.15.
What is the appropriate test procedure to determine whether there is a systematic difference between the assessments of Doctor A vs. Doctor B?
Table 8.15 Reproducibility of assessment of number of palpable lymph nodes among sexual contacts of AIDS or ARC patients
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Chapter 8 Solutions
Fundamentals of Biostatistics
- The authors of the paper "Statistical Methods for Assessing Agreement Between Two Methods of Clinical Measurement"† compared two different instruments for measuring a person's ability to breathe out air. (This measurement is helpful in diagnosing various lung disorders.) The two instruments considered were a Wright peak flow meter and a mini-Wright peak flow meter. Seventeen people participated in the study, and for each person air flow was measured once using the Wright meter and once using the mini-Wright meter. Subject Mini-WrightMeter WrightMeter Subject Mini-WrightMeter WrightMeter 1 512 494 10 445 433 2 430 395 11 432 417 3 520 516 12 626 656 4 428 434 13 260 267 5 500 476 14 477 478 6 600 557 15 259 178 7 364 413 16 350 423 8 380 442 17 451 427 9 658 650 (a) Suppose that the Wright meter is considered to provide a better measure of air flow, but the mini-Wright meter is easier to transport and to use. If the two types of meters produce…arrow_forwardRecent research indicates that the effectiveness of anti-depressant medication is directly related to the severity of the depression (Khan, Brodhead. Kolts, and Brown, 2005). Based on pre-treatment dcprcssion scores, paticnts werc divlded into four groups based on their level of depi ession. After receiving the antidepression medication, depi ession scores were measured again and the amount of improvement was recorded for cach pcrsion. The following data are similar to the results of the study. Moderately High Moderate Moderate Low Severe Severe 4 5 N= 16 2 3 6 6 G= 48 +a 2 2. 2 6 ΣΧ- 2 4 M=2.5 M=2 M=4 M-5 T= 10 T= 8 T= 16 T=20 SS=. .. SS=2 SS=8 SS- 6 A, Complete the places marking by ... and answer the question whether the data indicate significant difference among the four levels of severity? Test with a= 0.05. B, Compute n', the percentage of variance expressed by group difference.arrow_forwardA study was made of 1,057 cases of poisoning in children treated as inpatients at Milwaukee Children's Hospital from 1962 through 1968. Data on date of occurrence, age and sex of the child, and type of agent involved were recorded and analyzed by standard statistical methods. Poisoning was due to ingestion of aspirin in 35 per cent of the children studied and to the ingestion of hydrocarbon distillates in 18 per cent. A statistically significant male dominance was found for ingestion of hydrocarbons; age-specific peaks were found for some categories. Trends as to the relative and absolute frequencies of each specific poison from one year to the next were noted; possible reasons for increasing or decreasing trends are discussed. Is this study descriptive or inferential? Explain your answer. What are the variables used in the study? In your opinion, what level of measurement was used to obtain the data from the variables? Does the article define the population? If so, how is it…arrow_forward
- One study of cell phones and the risk of brain cancer looked at a group of 469 people who have brain cancer. The investigators then asked about the use of cell phones. Result: “Our data suggest that the use of hand- held cellular phones is not associated with risk of brain cancer. B . Based on this study, can you determine that cellular use does not CAUSE brain cancer? Why or why not?arrow_forwardA study is designed to test whether there is a difference in mean daily calcium intake in adults with normal bone density, adults with osteopenia (a low bone density which may lead to osteoporosis) and adults with osteoporosis. Adults 60 years of age with normal bone density, osteopenia and osteoporosis are selected at random from hospital records and invited to participate in the study. Each participant's daily calcium intake is measured based on reported food intake and supplements. The data are shown below. Is there a statistically significant difference in mean calcium intake in patients with normal bone density as compared to patients with osteopenia and osteoporosis?arrow_forward1) Soda consumption is very common in the U.S. For the purposes of this question, assume that 30% of the population consumes the equivalent of 3 or more 12 oz. sodas per week (this is the prevalence of the exposure). A large multi-center cohort study was conducted to evaluate the association between soda consumption and risk of diabetes. At baseline, participants were asked about their typical soda consumption, and individuals who reported consuming 3 or more sodas per week were considered exposed. Participants were followed for 10 years, and the following results were obtained: Incident Cases of Diabetes 356 236 Person-Years Contributed 3+ sodas a week 375234 <3 sodas a week 399763 a) Name the appropriate measure of association corresponding to the excess rate of diabetes attributable to soda consumption among subjects who consume 3+ sodas per week. Calculate this measure (shown as a rate, using the correct units), and provide a brief interpretation of your answer b) Calculate the…arrow_forward
- 6. Binge-watching a television show might not be the best way to enjoy a television series (Horvath et al., 2017). Participants in an experiment were in a group that either watched an entire tv series during daily one-hour sessions or watched all the episodes during a single binge session. Participants were asked to rate their enjoyment of the t.v. series on a scale of 0-100. Data like those observed by the author are listed below: Binge-watched 87 Daily-watched 84 71 100 73 87 86 97 78 92 a. Is there a difference in the level of enjoyment based on whether the series was binge-watched or watched on a daily basis? Use a two-tailed test at the a = 0.05 level of significance? b. Do the data analysis in SPSS in addition to your hand calculations. Attach a printout of your results.arrow_forwardVasectomies and Prostate Cancer. In the United States, approximately 450,000 vasectomies are performed each year. In this surgical procedure for contraception, the tube carrying sperm from the testicles is cut and tied. Several studies have been conducted to analyze the relationship between vasectomies and prostate cancer. The results of one such study by E. Giovannucci et al. appeared in the paper “A Retrospective Cohort Study of Vasectomy and Prostate Cancer in U.S. Men” (Journal of the American Medical Association, Vol. 269(7), pp. 878–882). Of 21,300 men who had not had a vasectomy, 69 were found to have prostate cancer; of 22,000 men who had had a vasectomy, 113 were found to have prostate cancer. a. At the 1% significance level, do the data provide sufficient evidence to conclude that men who have had a vasectomy are at greater risk of having prostate cancer? Consider men who had had a vasectomy Population 2. b. Is this study a designed experiment or an observational study?…arrow_forwardAn epidemiologist found five cases of “big toe cancer” in the Yukon Territory. Because there were only a few cases, the epidemiologist decided to conduct a matched case-control study to determine whether shoe size larger than 9 is a risk factor for big toe cancer. Cases were individually matched to one control for daily activity, history of athlete’s foot, and history of ingrown toenails. The following data were gathered: Shoe size > 9 Pair Case Control 1 Yes No 2 No No 3 No Yes 4 Yes Yes 5 No Yes Compute the proper measure of association. Interpret your results. If you were to investigate a rare cancer in Lynchburg, where might you look for data? What would be necessary legally and ethically to be able to utilize this data set(s)? Submit your thread by 11:59 p.m. (ET) on Thursday of Module/Week 3, and submit your replies by 11:59 p.m. (ET) on Sunday of the same module/week. 1arrow_forward
- Glencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw HillCollege Algebra (MindTap Course List)AlgebraISBN:9781305652231Author:R. David Gustafson, Jeff HughesPublisher:Cengage LearningBig Ideas Math A Bridge To Success Algebra 1: Stu...AlgebraISBN:9781680331141Author:HOUGHTON MIFFLIN HARCOURTPublisher:Houghton Mifflin Harcourt