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
- helparrow_forwardBody Fat. J. McWhorter et al. of the College of Health Sciences at the University of Nevada, Las Vegas, studied physical therapy students during their graduate-school years. The researchers were interested in the fact that, although graduate physical-therapy students are taught the principles of fitness, some have difficulty finding the time to implement those principles. In the study, published as “An Evaluation of Physical Fitness Parameters for Graduate Students” (Journal of American College Health, Vol. 51, No. 1, pp. 32–37), a sample of 27 female graduate physical-therapy students had a mean of 22.46 percent body fat. a. Assuming that percent body fat of female graduate physicaltherapy students is normally distributed with standard deviation 4.10 percent body fat, determine a 95% confidence interval for the mean percent body fat of all female graduate physical-therapy students. b. Obtain the margin of error, E, for the confidence interval you found in part (a). c. Explain the…arrow_forwardAn oil company plans to add a chemical to its gasoline to make it burn more cleanly. The company conducts an experiment to see whether adding the chemical affects the gasoline mileage of cars using their gasoline. State the null hypothesis for the experiment. Adding the chemical increases gas mileage. Adding the chemical does not affect gasoline mileage. Adding the chemical affects gasoline mileage. Adding the chemical decreases gasoline mileage.arrow_forward
- Calcium is the most abundant mineral in the human body and has several important functions. Most of the body calcium is stored in the bones and teeth, where it functions to support their structure. Recommendations for calcium are provided in Dietary Reference Intakes, developed by the Institute of Medicine of the National Academy of Sciences. The recommended adequate intake (RAI) for calcium for adults (ages 19-50) is 1000 mg per day. A random sample of 18 adults with incomes below the poverty level gave the following calcium intakes:886 633 943 847 934 8411193 820 774 834 1050 10581192 975 1313 872 1079 809Assume the population standard deviation for daily calcium intake for adults with incomes below the poverty level is 188mg.At the 0.05 level of significance, does the data provided above provide evidence to suggest that the mean calcium intake of all adults with incomes below the poverty level is less than the RAI pf 1000mg per day? Step 1: Define the parameter & setup the…arrow_forwardA drug treatment can sometimes be affected by the use of another drug taken concomitantly. This is why doctors and pharmacists routinely ask patients about all the drugs they use, even the ones available over the counter. One study examined the impact of nonsteroidal anti-inflammatory drugs (NSAIDs) on the efficacy of the antidepressant citalopram in clinically depressed individuals. Data from a large clinical trial were reviewed, and clinical remission from depressive symptoms was assessed for individuals who had taken NSAIDs concomitantly and those who had not. The findings are given in the table. NSAID use No NSAID use Remission 182 628 No remission 227 509 How strong is the evidence that concomitant NSAID use lowers the effectiveness of the antidepressant citalopram? Follow the four-step process.arrow_forwardA study was conducted to examine the effect of diet cola consumption on calcium levels in women. A sample of 16 healthy women aged 18 to 40 were randomly assigned to drink 24 ounces of either diet cola or water. Their urine was collected for three hours after ingestion of the beverage and calcium excretion (in mg) was measured. The data are stored in ColaCalcium.arrow_forward
- Your cognitive capacity is significantly reduced when your smartphone is within reach, even if it’s off. A professor conducted experiments with nearly 600 smartphone users in an attempt to measure how well people can complete tasks when they have their smartphones nearby even when they’re not using them. In one experiment, the researchers asked study participants to sit at a computer and perform a task that required full concentration in order to succeed. The tests were geared to measure participants’ available cognitive capacity – that is, the brain’s ability to hold and process data at any given time. Before beginning, participants were randomly instructed to place their smartphones either on the desk face down (group 1; 200 participants), in their pockets (group 2; 200 participants), or in another room (group 3; 200 participants). All participants were instructed to turn their phones to silent. The researchers found that participants with their phones in another room significantly…arrow_forwardAugmented Reality (AR) is a technology that superimposes a computer-generated image on a user's view of the real world, and it is believed that it will soon affect the conventional learning process. A random sample of nine university students was selected to test for the effectiveness of a special course on augmented reality in learning. They were taught how to incorporate AR into their learning process to its full potential. Table 1 gives the scores in a Learning Effectiveness test given to these students before and after attending this course. Question: Test at the 1% significance level whether this AR course makes any statistically significant improvement in the learning effectiveness of all university students.arrow_forwardHoaglin, Mosteller, and Tukey (1983) presented data on blood levels of beta-endorphin as a function of stress. They took beta-endorphin levels for 19 patients 12 hours before surgery and again 10 minutes before surgery. The data are presented below, in fmol/ml Based on these data, what effect does increased stressed have on endorphin levels. What type of test is this? Participant 12 hours before 10 minutes before 1 10 6.5 2 6.5 14.0 3 8.0 13.5 4 12 18 5 5.0 14.5 6 11.5 9.0 7 5.0 18.0 8 3.5…arrow_forward
- You are concerned that nausea may be a side effect of Tamiflu, but you cannot just give Tamiflu to patients with the flu and say that nausea is a side effect if people become nauseous. This is because nausea is common for people who have the flu. From past studies you know that about 32% of people who get the flu experience nausea. You collected data on 1970 patients who were taking Tamiflu to relieve symtoms of the flu, and found that 683 experienced nausea. Use a 0.01 significance level to test the claim that the percentage of people who take Tamiflu for the relief of flu symtoms and experience nausea is greater than 32%. a) Identify the null and alternative hypotheses? Ho: ? H1: ? b) What type of hypothesis test should you conduct (left-, right-, or two-tailed)? O left-tailed right-tailed two-tailed c) Identify the appropriate significance level. d) Calculate your test statistic. Write the result below, and be sure to round your final answer to two decimal places. e) Calculate your…arrow_forwardThe cholesterol-reducing drug Lipitor consists of atorvastatin calcium. Results (based on data from the company Parke-Davis) summarising the incidence of headaches as an adverse reaction in clinical tests are given below. We are interested in evaluating the evidence that the incidence of headaches is dependent on the amount of atorvastatin used. Placebo Atorvastatin 10 mg Atorvastatin 20 mg Atorvastatin 40 mg Atorvastatin 80 mg Headache 19 47 6 2 6 No headache 251 816 30 77 88 1. If level of atorvastatin was independent of incidence of headaches, what would be the expected frequency in the headache and 20 mg cell? Would this cause any concern for a test of independence of these factors? Why? 2. Combine the 20 mg and 40 mg results into one column, then perform a chi-squared hypothesis test at the 1% significance level to evaluate the evidence that the incidence of headaches is dependent on the amount of atorvastatin used.arrow_forwardA sleep researcher is assessing the impact of melatonin supplements on time to fall asleep for individuals with insomnia. She recruited 30 participants with insomnia and assigned 14 of them to take melatonin before sleeping. The researcher then recorded time to fall asleep (in minutes) for each participant. The researcher's hypothesis was that participants in the melatonin group would fall asleep faster than participants in the control group. The data collected are displayed below together with some descriptive statistics. Melatonin- 72, 59, 76, 64, 40, 51, 39, 69, 69, 78, 66, 100, 43, 45,59,64,51 M = 62.21 SD = 17.33 Control- 52, 80, 113, 111, 103, 96, 64, 56, 112, 102, 100, 102, 101, 58, 117, 101,80,111,96,56,102 M = 91.75 SD = 22.16 a) Does the researcher have enough evidence to reject the null hypothesis at an alpha level of .01? Follow the steps involved in hypothesis testing and make a decision regarding the null hypothesis based on the comparison between the critical value and…arrow_forward
- Linear Algebra: A Modern IntroductionAlgebraISBN:9781285463247Author:David PoolePublisher:Cengage Learning