9) Researchers are interested in studying the health effects of 1-bromopropane, a solvent touted as a"green replacement" for ozone-depleting chemicals which has been shown in laboratory studies to bea potential lung carcinogen. Although it is commonly used in several commercial industries, highlevels of exposure, of the magnitude required to cause cancer in model organisms, are rare in thegeneral population. If we consider lung cancer to be a relatively common outcome, which of thefollowing study designs would be most appropriate for determining whether 1-bromopropane isassociated with lung cancer risk:a) Cross-sectional studyb) Cohort studyc) Experimental studyd) Ecologic studye) Case-control study10) What is the null hypothesis for the study described above (Question 9)?

9) Cohort study refers to the study of subjects to determine whether the factor of interest is…

Answered: 9) Researchers are interested in…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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Beryllium is an extremely lightweight metal that is used in many industries, such as aerospace and electronics. Long-term exposure to beryllium can cause people to become sensitized. Once an individual is sensitized, continued exposure can result in chronic beryllium disease, which involves scarring of the lungs. In a study of the effects of exposure to beryllium, workers were categorized by their duration of exposure (in years) and by their disease status (diseased, sensitized, or normal). The results were as follows: Duration of Exposure <1 1 to <5 ≥5 Diseased 14 13 18 Sensitized 11 20 15 Normal 78 140 209 Test the hypothesis of independence. Use the a=0.10 level of significance and the P-value method with the TI-84 Plus calculator. What do you conclude? State the null and alternate hypotheses.
Two groups, A and B, consist of 100 people each who have a disease. A serum is given to group A but not to group B (which is called the control). It is found that in groups A and B, 75 and 65 people, respectively, recover from the disease. At significant levels of (a) 0.01, (b) 0.05, test the hypothesis that the serum helps cure the disease.
In an observational study, it was noticed that people that eat more chocolate tend to have better blood flow than the general population. Researchers wonder whether the improved blood flow might be caused by flavanols (a molecule found in many foods). Dark chocolate contains a high concentration of flavanols, but milk chocolate contains a much lower concentration. How could the researchers design an experiment to determine the effects of flavanol on blood flow from the different types of chocolate?
DDT (dichlorodiphenyltrichloroethane) was used extensively from 1940 to 1970 as an insecticide. It still sees limited use for control of disease. But DDT was found to be harmful to plants and animals, including humans, and its effects were found to be lasting. The amount of time that DDT remains in the environment depends on many factors, but the following table shows what can be expected of 200 kilograms of DDT that has seeped into the soil. t = time in yearssince application D = DDT remaining,kilograms 0 200.00 1 190.00 2 180.50 3 171.48 (a) Show that the data are exponential. The ratio from year 0 to year 1 is ______ , from year 1 to year 2 is ____ , and from year 2 to year 3 is_____ (rounded to two decimal places). Because these successive ratios are all , a) different b)the same , the data are exponential.
We have a sample of 2,400 geriatric patients who are in an assisted living home, of which 1,200 participated in a new preventative Drug A. Rates of UTIs tend to be higher than average among this population. As part of a preventative and treatment intervention, we are examining the performance of several drugs: Preventative Drug (before the onset of UTI) Drug A: preventative UTI drug taken daily in hopes to prevent the growth of bacteria that causes UTIs Treatment Drugs (after the onset of UTI) Drug B: New antibiotic for treating UTIs Drug C: Conventional antibiotic for treating UTIs Information for how many patients took each drug or combination of drugs is summarized below in the two tables. Use these to answer questions a) -d) Table 1. Summary of performance of drug A: UTI rates among those taking and not taking drug A Did not take Drug A Did take Drug A Total UTI 759 887 1646 No UTI 441 312 753 Total 1200 1200 2400 Table 2. Summary of performance of drug B and C: recovery…
Patients immobilized for a substantial amount of time can develop deep vein thrombosis (DVT), a blood clot in a leg or pelvis vein. DVT can have serious adverse health effects and can be difficult to diagnose. On its website, drug manufacturer Pfizer reports the outcome of a study looking at the effectiveness of the drug Fragmin (dalteparin) in preventing DVT in immobilized patients. Of the 1518 randomly chosen immobilized patients given Fragmin, 42 experienced a complication from DVT. Of the 1473 randomly chosen immobilized patients given a placebo, 73 experienced a complication from DVT. Compute the proportion (risk) of patients experiencing DVT complications for immobilized patients treated with Fragmin. (Enter the proportion with 4 decimal places. DO NOT enter the percent.)
Although arsenic is known to be a poison, it also has some beneficial medicinal uses. In one study of the use of arsenic to treat acute promyelocytic leukemia (APL), a rare type if blood cancer, APL patients were given an arsenic compound as part of their treatment. Of those receiving arsenic, 32% were in remission and showed no signs of leukemia in subsequent examination. It is known that 18% of APL patients go into remission after conventional treatment. Suppose that the study had included 100 randomly selected patients. Is there sufficient evidence to conclude that the proportion in remission for the arsenic treatment is greater than 0.18, the remission proportion for conventional treatment? a. Test the hypothesis at the 0.01 significance level. b. Construct and interpret a 99% confidence interval for the true proportion of APL patients who go into remission after using arsenic. Does the inference drawn from this interval match the conclusion from the test that you did in part…
There have been many studies recently concerning coffee drinking and cholesterol level. While it is known that several coffee-bean components can elevate blood cholesterol level, it is thought that a new type of paper coffee filter may reduce the presence of some of these components in coffee. The effect of the new filter on cholesterol level will be studied over a 10-week period using 300 nonsmokers who each drink 4 cups of caffeinated coffee per day. Each of these 300 participants will be assigned to one of two groups: the experimental group, who will only drink coffee that has been made with the new filter, or the control group, who will only drink coffee that has been made with the standard filter. Each participant’s cholesterol level will be measured at the beginning and at the end of the study. Which test would you conduct to determine whether the change in cholesterol level would be greater if people used the new filter rather than using the standard filter? Why would the…
There have been many studies recently concerning coffee drinking and cholesterol level. While it is known that several coffee-bean components can elevate blood cholesterol level, it is thought that a new type of paper coffee filter may reduce the presence of some of these components in coffee. The effect of the new filter on cholesterol level will be studied over a 10-week period using 300 nonsmokers who each drink 4 cups of caffeinated coffee per day. Each of these 300 participants will be assigned to one of two groups: the experimental group, who will only drink coffee that has been made with the new filter, or the control group, who will only drink coffee that has been made with the standard filter. Each participant’s cholesterol level will be measured at the beginning and at the end of the study. Describe an appropriate method for assigning the subjects to the two groups so that each group will have an equal number of subjects. In this study, the researchers chose to include a…
A biochemist is testing the effect of a new antibiotic on a particular
Zika and male reproduction. The Zika virus, which is known to be transmitted by mosquitoes, can also be transmitted sexually, as the virus can persist for weeks in the semen of symptom-free infected men. Using a mouse model, researchers examined the impact of Zika on male reproductive organs. Young adult male lab mice of a breed susceptible to Zika were either inoculated with Zika or not. Here are the weights of their testes two weeks later (in grams, g) Uninfected 85 85 90 91 96 100 Infected 17 93 15 12 10 9 10 12 a) What two populations do the researchers want to compare and what is the response variable? b) State the null and alternative hypotheses. Plot the data and check the conditions for inference. Explain why a two-sample t test is not appropriate here.
A deficiency of the trace element selenium in the diet can negatively impact growth, immunity, muscle and neuromuscular function, and fertility. The introduction of selenium supplements to dairy cows is justified when pastures have low selenium levels. Authors of a research paper supplied the following data on milk selenium concentration (mg/L) for a sample of cows given a selenium supplement (the treatment group) and a control sample given no supplement, both initially and after a 9-day period. Initial Measurement Treatment Control 11.4 9.1 9.6 8.7 10.1 9.7 8.5 10.8 10.2 10.9 10.6 10.6 11.9 10.1 9.9 12.3 10.7 8.8 10.2 10.4 10.3 10.9 11.4 10.4 9.3 11.6 10.6 10.9 10.9 8.3 After 9 Days Treatment Control 138.3 9.2 104 8.9 96.4 8.9 89 10.1 88 9.6 103.8 8.6 147.3 10.4 97.1 12.4 172.6 9.2 146.3 9.5 99 8.4 122.3 8.8 103 12.5 117.8 9.1 121.5 93 (a) Use the given data for the treatment group to determine if…

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