The article “Brain Shunt Tested to Treat Alzheimer’s” (San Francisco Chronicle, October 23, 2002) summarizes the findings of a study that appeared in the journal Neurology. Doctors at Stanford Medical Center were interested in determining whether a new surgical approach to treating Alzheimer’s disease results in improved memory functioning. The surgical procedure involves implanting a thin tube, called a shunt, which is designed to drain toxins from the fluid-filled space that cushions the brain. Eleven patients had shunts implanted and were followed for a year, receiving quarterly tests of memory
- a. What were the researchers trying to learn? What questions motivated their research?
- b. Do you think that the study was conducted in a reasonable way? What additional information would you want in order to evaluate this study?
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Chapter 1 Solutions
Introduction To Statistics And Data Analysis
- Suppose a researcher is interested inthe effectiveness in a new childhood exercise program implemented in a SRS of schools across a particular county. In order to test the hypothesis that the new program decreases BMI (Kg/m2), the researcher takes a SRS of children from schools where the program is employed and a SRS from schools that do not employ the program and compares the results. Assume the following table represents the SRSs of students and their BMIs. Student intervention group BMI (kg/m2) Student control group BMI (kg/m2) A 18.6 A 21.6 B 18.2 B 18.9 C 19.5 C 19.4 D 18.9 D 22.6 E 24.1 F 23.6 A) Assuming that all the necessary conditions are met (normality, independence, etc.) carry out the appropriate statistical test to determine if the new exercise program is effective. Use an alpha level of 0.05. Do not assume equal variances.B) Construct a 95% confidence interval about your estimate for the average difference in BMI between the groups.arrow_forwardAn article in Knee Surgery, Sports Traumatology, Arthroscopy, "Arthroscopic meniscal repair with an absorbable screw: results and surgical technique," (2005, Vol. 13, pp. 273-279) cites a success rate of 1% for meniscal tears with a rim width of less than 3 mm, and a 1% success rate for tears from 3-6 mm. If you are unlucky enough to suffer a meniscal tear of less than 3 mm on your left knee, and one of width 3-6 mm on your right knee, what is the probability that you have exactly one successful surgery? assume surgieries are independent.arrow_forwardThe Diabetes Control and Complications trial research group, randomly assigned volunteers with type 1 (insulin-dependent) diabetes mellitus, but without retinopathy, either to a conventional treatment or to a more intensive treatment aimed at maintaining normal blood glucose levels. The volunteers' health was monitored closely for approximately six years. By the end of the study, 91 patients out of 378 in the conventional treatment group had developed retinopathy, whereas 23 out of 348 in the intensive treatment group had developed retinopathy. Test whether the rates of retinopathy differed significantly between the two treatment groups, if they did, which rate was significantly lower. 1. Provide the null hypothesis 2. Provide the alternative hypotheses 3. calculate the appropriate test statistic. Show all work 4. Identify the p-value for that test statistic 5. Using the p-value method and an alpha level of 0.02 state what your conclusions are regarding the null hypothesis, and…arrow_forward
- The Diabetes Control and Complications trial research group, randomly assigned volunteers with type 1 (insulin-dependent) diabetes mellitus, but without retinopathy, either to a conventional treatment or to a more intensive treatment aimed at maintaining normal blood glucose levels. The volunteers' health was monitored closely for approximately six years. By the end of the study, 91 patients out of 378 in the conventional treatment group had developed retinopathy, whereas 23 out of 348 in the intensive treatment group had developed retinopathy. Test wether the rates of retionpathy differed significantly betweenthe two treatment groups, if they did, which rate was significantly lower. 1. Provide the null hypothesis 2. Provide the alternative hypotheses 3. calculate the appropriate test statistic. Show all work 4. Indentify the p-value for that test statistic 5. Using the p-vlaue method and an alpha level of 0.02 state what your conclusions is regarding the null hypothesis, and…arrow_forwardIn a study attempting to replicate findings by Stephens, Atkins, & Kingston (2009), each participant was asked to plunge a hand into the icy water and keep it there as long as the pain would allow. In one condition, the participants repeated their favorite curse words while their hands were in the water. In the other condition, they repeated neutral words. The original research showed that, in addition to lowering the participants’ perception of pain, swearing also increased the amount of time they were able to tolerate the pain. Data similar to the results obtained in the study are shown in the following table: _____________Amount of Time (in Seconds)_ Participant Swear Words Neutral Words 1 94 59 2 70 61 3 52 47 4…arrow_forwardIn a study attempting to replicate findings by Stephens, Atkins, & Kingston (2009), each participant was asked to plunge a hand into the icy water and keep it there as long as the pain would allow. In one condition, the participants repeated their favorite curse words while their hands were in the water. In the other condition, they repeated neutral words. The original research showed that, in addition to lowering the participants’ perception of pain, swearing also increased the amount of time they were able to tolerate the pain. Data similar to the results obtained in the study are shown in the following table: _____________Amount of Time (in Seconds)_ Participant Swear Words Neutral Words 1 94 59 2 70 61 3 52 47 4…arrow_forward
- Dyslexia refers to a specific reading disability that affects 10% to 15% of the general population. A dyslexic child is defined as a child of normal or above-normal intelligence with no known organic behavioural disorders who, despite normal schooling, shows a reading lag of at least two years. A researcher proposed that dyslexia was the result of a complex visual deficit that could be immediately corrected by simply putting a blue plastic overlay on the reading material. To test this, 100 dyslexic children were randomly assigned to one of two groups, one of which read from pages with a clear plastic overlay and the other of which read from pages with a blue plastic overlay. The dependent variable was percentage correct on a multiple-choice reading comprehension test. a) Is this an observational study or an experiment? Explain your choice. b) Why did the researcher use a clear overlay as one of the treatment groups instead of just having the children read the passage without an…arrow_forwardA heart study objective was to study heart disease among healthy volunteers.After a 10-year follow-up period involving men aged 40 to 59, there were 16 casesof coronary heart disease (CHD) among the 454 men who initially had cholesterollevels below 210 mg/100 ml (referred to as the low serum cholesterol group). Incontrast, among the 424 men whose initial cholesterol levels were at least 245mg/100 ml (referred to as the high serum cholesterol group), there were 51 cases ofCHD. With this information, Draw a 2x2 contingency table then calculate the relative risk (RR) associated with high serum cholesterol and provide an interpretation of the result.arrow_forwardStudies have shown that omega-3 fatty acids have a wide variety of health benefits. Omega-3 oils can be found in foods such as fish, walnuts, and flaxseed. A company selling milled flaxseed advertises that one tablespoon of the product contains, on average, at least 3800 mg of ALNA, the primary omega-3. a) The company plans to conduct a test to ensure that there is sufficient evidence that its claimiscorrect. Tobesafe,thecompanywantstomakesurethatevidenceshowsthe average is higher than 3800 mg. What are the null and alternative hypotheses? b) Suppose, instead, that a consumer organization plans to conduct a test to see if there is evidence against the claim that the product contains an average of 3800 mg per tablespoon. The consumer organization will only take action if it finds evidence that the claim made by the company is false and that the actual average amount of omega-3 is less than 3800 mg. What are the null and alternative hypotheses?arrow_forward
- A consumer group is investigating a producer of diet meals to examine if its prepackaged meals actually contain the advertised 6 ounces of protein in each package. Based on the following data, is there any evidence that the meals do not contain the advertised amount of protein? Run the appropriate test at a 5% level ofarrow_forwardA biochemist is testing the effect of a new antibiotic on a particulararrow_forwardResearch done at the Harvard School of Public Health showed that regular soda drinkers may have a tendency toward the weak and brittle bones associated with osteoporosis. They surveyed 2,622 women who were active athletes in college and classified them as to whether they regularly drank soft drinks or rarely drank soft drinks. The proportion of women in each group who suffered from bone fractures was determined. The findings: those who regularly drank soft drinks were twice as likely to suffer from bone fractures as those who rarely drank soft drinks. Source: Health and Fitness News Service, August 21, 1996. a. Was this an observational study or an experiment? Explain.b. What is the population under study?c. What was the explanatory variable?d. What was the response variable?e. What are some possible confounding variables in this study?arrow_forward
- Linear Algebra: A Modern IntroductionAlgebraISBN:9781285463247Author:David PoolePublisher:Cengage Learning