Please answer and follow all questions/instructions below: Chapter 18 Problems:

Please answer and follow all questions/instructions below:
Chapter 18 Problems: 1-4, 8, 21, 29
Chapter 19 Problems: 1, 5, 14, 33, 37
Chapter 20 Problems: 1, 23, 30
Each situation described in Exercises 18.1 to 18.4 requires inference about a mean or means. Identify the response variable and whether the setting involves (1) a single sample, (2) matched pairs, or (3) two independent samples.
18.1 The physiological blind spot refers to a very small zone of functional blindness in the eye where the optic nerve passes through the retina. We do not notice it because our nervous system compensates for it. Can eye training reduce the size of a person’s physiological blind spot? Researchers recruited a representative sample of 10 adults with normal vision. Each participant performed training exercises with one eye for three weeks. The size of the physiological blind spot was measured (in degrees of visual angle squared) with a motion detection task both prior to training and again after the training was completed.
18.2 Agricultural pests can be controlled to some extent either by using pesticides to kill them or by introducing a large number of sterilized males to diminish the species’ reproductive potential. Ten large corn fields are treated with pesticides, and 10 have sterilized males introduced. Corn yield (in bushels per acre) at harvest time is then compared for the two treatments.
18.3 To check a new analytical method, a chemist obtains a reference specimen of known concentration from the National Institute of Standards and Technology. She then makes 20 measurements of the concentration of this specimen with the new method and checks for bias by comparing the mean result with the known concentration.
18.4 People who sustain a concussion or a traumatic brain injury (TBI) are likely to experience sleep problems. Do these problems persist? Researchers recruited a sample of 31 patients who had their first ever TBI 18 months earlier and a control group of 42 otherwise similar individuals without prior brain trauma. They compared sleep duration per 24 hours (recorded electronically over a two-week period) for the two groups.
18.8 In 2015, people all over the internet were hotly debating whether a specific dress was actually white and gold (WG) or black and blue (BB). The photograph was unusually lit and provided little context beyond the dress itself, leaving much to interpretation. The dress therefore made an excellent tool to study the involvement of higher cognitive functions in color perception. Researchers recruited a random sample of adults, some of whom perceived the dress to be WG and some of whom perceived it to be BB. While the subjects were looking at the picture of the dress on a computer screen, their relative brain activity in the frontal cortex was assessed using functional magnetic resonance imaging (fMRI) brain imaging. Here are the findings:
BB − 0.68 − 0.58 − 0.57 − 0.42 − 0.39 − 0.36 − 0.30
− 0.21 − 0.23 − 0.14 − 0.12 − 0.08 0.04 0.20
WG − 0.24 − 0.03 0.07 0.15 0.16 0.17 0.33
0.35 0.37 0.49 0.52 0.54 0.68 0.76
Do the data give significant evidence that, on average, brain activity in the frontal cortex differs based on how the dress is perceived?
18.21 The central tail feathers of the long-tailed finch (Poephila acuticauda) are a sexually dimorphic trait hypothesized to play a role in sexual selection. The longer tail feathers in males cost energy to produce, and this is thought to signal the male’s excellent health condition. Here are the lengths of the central tail feathers (average of the two central feathers, in millimeters) of 20 male and 21 female long-tailed finches:
Males
87 77 95 73 74 85 56 86 95 108
75 87 73.5 82 89 64 74.5 87 85 86
Females
60 59 72 54 65 58 59 60 65 60
68 70.5 80 87 65 59 65 67 62 66
70
a. Treat these data as SRSs from the population of adult long-tailed finches in the wild. Make plots of both data sets and determine whether the use of a two-sample t procedure is appropriate.
b. How much longer, on average, are the central tail feathers of male long-tailed finches than those of the females? Give a 95% confidence interval for the difference in population mean length between the male and the female adult long-tailed finches.
18.29 Avandia (rosiglitazone maleate) is an oral antidiabetic drug produced by the pharmaceutical company GlaxoSmithKline. Before a drug can be prescribed, we must know how the body absorbs and excretes it. Patients were given a single dose of either 1 milligram (mg) or 2 mg of rosiglitazone maleate, and the maximum plasma concentration of the drug (in nanograms per milliliter, ng/ml) was assessed.
Treatment n x¯ s
1 mg 32 76 13
2 mg 32 156 42
Is there significant evidence that maximum plasma concentration is dose-dependent (that is, higher doses result in higher concentrations)?
19.1 A sample of 1714 cultures from individuals in Florida diagnosed with a strep infection was tested for resistance to the antibiotic penicillin; 973 cultures showed partial or complete resistance to the antibiotic.
a. Describe the population and explain in words what the parameter p is.
b. Give the numerical value of the statistic p^ that estimates p.
19.5 Exercise 19.1 gave data about the resistance of strep cultures to the antibiotic penicillin. Give a 95% confidence interval for the proportion of strep cultures from Florida patients showing partial or complete resistance to penicillin.
19.14 Gregor Mendel has been called the “father of genetics,” having formulated laws of inheritance even before the function of DNA was discovered. In one famous experiment with peas, Mendel crossed pure breeds of plants that produced either smooth peas or wrinkled peas. The first-generation peas were all smooth. In the second generation (F2), he obtained 5474 smooth peas and 1850 wrinkled peas. Do these data agree with the conclusion of 75% dominant-trait (in this case “smooth”) occurrence in F2? Conduct a hypothesis test.
19. 33 A study was designed to determine whether dogs can be trained to identify urine specimens from individuals with bladder cancer. Dogs were first trained to discriminate between urine specimens from patients with bladder cancer and urine specimens from patients with other conditions. After the training was completed, the dogs had to pick one of seven new urine specimens. Each time, only one of the seven urine specimens came from a patient with bladder cancer. Out of 54 trials, the dogs identified the correct urine specimen 22 times.
a. If the dogs were simply picking a urine specimen at random, we would expect them to be correct, on average, 1 out of 7 times. The experiment was designed to test whether dogs can perform better than chance. State the null and alternative hypotheses for this test.
b. Obtain the test statistic and the P-value. What do you conclude?
19.37 The Gallup-Healthways Well-Being Index is a comprehensive survey of the health status of Americans. In 2009, the survey asked a random sample of 258,141 adults, “Have you ever been told by a physician or a nurse that you have depression?” Of these respondents, 43,884 answered “yes.” Estimate with 95% confidence the proportion of adults in America who have ever been told by a health professional that they have depression.
20.1 The secondary outcome of the experiment described in Example 20.1 was smoking abstinence six months after quitting. Verified abstinence was achieved at that point by 78 of the 355 subjects in the abrupt-cessation group and 53 of the 342 subjects in the gradual-cessation group. Give a 95% confidence interval for the difference between the proportions of smokers who still abstain from smoking six months after they stopped, when quitting either abruptly or gradually.
20.23 The drug AZT was the first drug that seemed effective in delaying the onset of AIDS in HIV-positive patients. Evidence for AZT’s effectiveness came from a large randomized comparative experiment. The subjects were 1300 HIV-positive volunteers who had not yet developed AIDS. The study assigned 435 of the subjects at random to take 500 milligrams of AZT each day, and another 435 subjects to take a placebo. (The others were assigned to a higher dose of AZT, but we will compare only the first two groups.) At the end of the study, 38 of the placebo recipients and 17 of the AZT recipients had developed AIDS. We want to test the claim that taking AZT lowers the proportion of infected people who will develop AIDS in a given period of time.
a. State the hypotheses and check that you can safely use the z procedures.
b. How significant is the evidence that AZT is effective?
c. The experiment was double-blind. Explain what this means.
(Comment: Medical experiments on treatments for AIDS and other fatal diseases raise hard ethical questions. Some people argue that because AIDS is always fatal, infected people should get any drug that has any hope of helping them. The counter-argument is that then we will never find out which drugs really work. The placebo recipients in this study were given AZT as soon as the results indicated that AZT was clearly more effective.)
20.30 Urban legend says that knuckle cracking is bad for you and will eventually lead to osteoarthritis of the hand joints. A retrospective case-control study of individuals who had received an X-ray of the right hand in the past five years enrolled 135 subjects with a confirmed diagnosis of hand osteoarthritis and 80 control subjects in the same age group. The study found that 24 subjects with hand osteoarthritis and 19 control subjects were habitual knuckle crackers. Is there good evidence that the proportion of knuckle crackers is greater among individuals with hand osteoarthritis? Does this support the urban legend about knuckle cracking?

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Chapter 18 Problems: appeared first on blitzarchive.com.