R3.22. Cell phone risks Researchers at the Washington UniversitySchool of Medicine randomly placed 480 rats into one of threechambers containing radio antennas. One group was exposedto digital cell phone radio waves, the second to analog cellphone waves, and the third group to no radio waves. Twoyears later, the rats were examined for signs of brain tumors.In June 2002, the scientists said that differences among thethree groups were not statistically significant.a) Is this a study or an experiment? Explain.b) Explain in this context what “not statistically significant"means.c) Comment on the fact that this research was funded byMotorola, a manufacturer of cell phones.

There are three groups : 1 : digital cell phone radio waves 2 : analog cell phone waves 3 : no…

Answered: R3.22. Cell phone risks Researchers at…

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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1.A randomized, controlled study was conducted to evaluate the potential benefits/harm of using acupuncture to treat migraine headaches. Researchers selected a representative sample of 326 migraine sufferers to participate in the study. Subjects in the study sample were randomized to either receive acupuncture treatments, or to a control group that did not receive any treatment. The outcome of interest was the self-reported headache severity scores recorded three months after randomization (on a scale of 0 to 100, higher scores = greater severity). The following graphic compares the distribution of severity scores at 3 months between the Acupuncture and Control groups:
A TA in statistics thinks that the format of the conferences and the timing of the assignments may affect students' assignment marks (out of 10). He decided to design three conferences with a different format: (1) with lecturing, (2) with demonstrating problems, and (3) with involving students in active problem-solving. Twelve students attended one of the conferences (four in each format) and asked to submit their assignments at week 3. Another twelve students attended one of the conferences but asked to submit their assignments at week 5. The data are tabled below: Assignment Week 3 Week 5 Lecture 6,7,5,7 5,5,4,5 Format Demo problems 7,8,8,9 6,7,7,6 Active problems 9,10,10,10 8,9,9,10 Note: ΣΣΣx=1385 Perform the ANOVA test and table the results, stating all critical values. State and explain what should be the follow-up analysis after the overall F-test if any (NO calculation but just explain).
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1. To determine whether using a cell phone while driving increases the risk of an accident, a researcher examines accident reports to obtain data about the number of accidents in which a driver was talking on a cell phone. A. Is this a randomized experiment or an observational study? B. Assume that the accident reports show that people were more likely to have an accident while talking on a cell phone. Could this result be due to confounding?
Birthweight In 2003 the Journal of the AmericanMedical Association reported a study examining thepossible impact of air pollution caused by the 9/11 attack New York’s World Trade Center on the weight ofbabies. Researchers found that 8% of 182 babies born tomothers who were exposed to heavy doses of soot andash on September 11 were classified as having low birthweight. Only 4% of 2300 babies born in another NewYork City hospital whose mothers had not been near thesite of the disaster were similarly classified. Does thisindicate a possibility that air pollution might be linked toa significantly higher proportion of low-weight babies?a) Was this an experiment? Explain. b) Test an appropriate hypothesis and state your conclu-sion in context. c) If you concluded there is a difference, estimate thatdifference with a confidence interval and interpret thatinterval in context.
A researcher is conducting an experimental study on the effect of aspirin on heart attack risk. In order to assign who will receive aspirin and who will receive a placebo, she first divides her study into three age groups (18-29, 30-49, and 50 or older). She then randomly assigns individuals within these age groups to either receive aspirin or the placebo. This is an example of a cluster ?
1. Write a complete paragraph in APA format describing the research question and your results. Question: A social psychologist records the number of outbursts among students at two schools. Assuming the same number of students were observed at each school, what is the sample size at each school, the decision to retain or reject the null hypothesis) and the effect size for this study based on the following statement? The number of outbursts among students at the small school (M=3) was significantly less than the number recorded at the large school (M = 5) f(38) =4.19, p < .05(d = 0.25 ). Results: sample size = 20 for each school For a two tailed test and df = 38, at 0.05 significance level, t = 2.023 (from t distribution table) Here, the critical value is less than t obtained (t2.023 < 4.19) Hence, we reject the null hypothesis at a 5% significance level Given that d = 0.25 => effect size is medium (since 0.2<d<0.8 for medium) Therefore, the study showed a medium…
A sociologist studying New York City ethnic groups wants to determine if there is a difference in income for immigrants from four different countries during their first year in the city. She obtained the data in the following table from a random sample of immigrants from these countries (incomes in thousands of dollars). Use a 0.05 level of significance to test the claim that there is no difference in the earnings of immigrants from the four different countries. Country I Country II Country III Country IV 12.3 8.3 20.4 17.3 9.1 17.2 16.5 8.7 10.9 19.2 22.8 14.2 8.8 10.2 5.5 21.4 16.1 19.2 19.3 (b) Find SSTOT, SSBET, and SSW and check that SSTOT = SSBET + SSW. (Round your answers to three decimal places.) SSTOT = SSBET = SSW = Find d.f.BET, d.f.W, MSBET, and MSW. (Round your answer to three decimal places for MSBET and MSW.) dfBET = dfW = MSBET = MSW = Find the value of the sample F statistic. (Round your answer to three decimal…
A sociologist studying New York City ethnic groups wants to determine if there is a difference in income for immigrants from four different countries during their first year in the city. She obtained the data in the following table from a random sample of immigrants from these countries (incomes in thousands of dollars). Use a 0.05 level of significance to test the claim that there is no difference in the earnings of immigrants from the four different countries. Country I Country II Country III Country IV 12.9 8.8 20.6 17.7 9.8 17.9 16.8 8.7 10.7 19.8 22.6 14.1 8.5 10.3 5.8 21.7 16.9 19.3 19.5 (b) Find SSTOT, SSBET, and SSW and check that SSTOT = SSBET + SSW. (Round your answers to three decimal places.) SSTOT = SSBET = SSW = Find d.f.BET, d.f.W, MSBET, and MSW. (Round your answer to three decimal places for MSBET and MSW.) dfBET = dfW = MSBET = MSW = Find the value of the sample F statistic. (Round your answer to three decimal…
A behavioral scientist investigated whether there is a significant difference in the percentages of men and women who purchase silver-colored cars. The scientist selected a random sample of 50 men and a random sample of 52 women who had recently purchased a new car. Of the men selected, 16 had purchased a silver-colored car. Of the women selected, 9 had purchased a silver-colored car. Which of the following is the most appropriate method for analyzing the results? A two-sample zz-test for the difference in population proportions A A two-sample zz-test for the difference in sample proportions B A one-sample zz-test for a sample proportion C A one-sample zz-test for a population proportion D A one-sample zz-test for a difference in sample proportions
1. Do social robots walk or roll? Refer to the International Conference on Social Robotics (Vol. 6414, 2010) study of the trend in the design of social robots, Exercise 2.1 (p. 26). Recall that in a random sample of 106 social (or service) robots designed to entertain, educate, and care for human users, 63 were built with legs only, 20 with wheels only, 8 with both legs and wheels, and 15 with neither legs nor wheels. One of the 106 social robots is randomly se- lected and the design (e.g., wheels only) is noted. a. List the simple events for this study. b. Assign reasonable probabilities to the simple events. c. What is the probability that the selected robot is designed with wheels? d. What is the probability that the selected robot is designed with legs? Toxic chemical incidents. Process Safety Progress (Sept. 2004) reported on an emergency response system for inci- dents involving toxic chemicals in Taiwan. The system has logged over 250 incidents since being implemented in 2000.…

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