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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4. A researcher interviews by phone a province-wide random sample of persons aged 18 and above about their attitude toward divorce. Using the following set of results, the hypothesis that the attitude of respondent toward divorce vary across gender was tested. 4. A researcher interviews by phone a province-wide random sample of persons aged 18 and above about their attitude toward divorce. Using the following set of results, the hypothesis that the attitude of respondent toward divorce vary across gender was tested. Table 1. Contingency Table Male Female Favor Not in favor 88 39 46 92 Table 2. Analysis Result Value df . Sig. (2-sided) Stat 17.922 1 .000 c. What statistical tool was used? d. Discuss the statistical result using the APA format
Q. 9 There are four McBurger restaurants in the Columbus, Georgia, area. The numbers of burgers sold at the respective restaurants for each of the last six weeks are shown below. Restaurant Week Metro University Interstate 160 220 River 1 124 320 190 2 234 340 230 430 105 240 290 310 280 3 290 240 4 245 170 5 205 180 310 260 270 205 At the 10% significance level, perform the test of significance for means of restaurants and weeks.
Sigall and Ostrove (1975) did an experiment to assess whether the physical attractiveness of a defendant on trial for a crime had an effect on the severity of the sentence given in a mock jury trials. Each of the participants in this study was randomly assigned to one of the following three treatment groups; every participant received a package that described a burglary and gave background information about the accused person. The three treatment groups differed in the type of information that they were given about the accused person’s appearance. Members of Group 1 were showing a photo of an attractive person; members of Group 2 were shown a photograph of an unattractive person; members of Group 3 saw no photograph. Some of their results are described here. Each participant was asked to assign a sentence (in years) to the accused person; the researchers predicted that more attractive persons would receive shorter sentences. a)Prior to assessment of the outcome, the researchers did a…
2. Juvenile free-living ground squirrels utilize responses known as "alarm calls" in response to predators. These calls can alert others to danger. Newly weaned squirrels emerge from the nest at about 25 days of age. Do the squirrels emerge with automatic responses to alarm signals, or are the responses learned? To answer this question, a biologist played recordings of alarm calls for three random samples from populations (by age) of squirrels and observed the squirrels' responses. She reasoned that if the responses were not different for the different age groups, the squirrels must be responding by instinct. On the other hand, if the responses differ with the age of the squirrels the young squirrels must be learning to respond to the alarm calls. Her data for the responses, categorized by age, is presented below: Response to alarm call Enter or Stand up or run to burrow freeze Totals Days since weaning 1-5 21 18 39 6-10 16 24 40 10-15 12 19 Totals 49 49 98 Is there convincing evidence…
2. We ask whether people will score higher or lower on a questionnaire of their well-being when they are exposed to sunshine compared to when they're not exposed to sunshine. A sample of 8 people is first measured after low levels of sunshine exposure and then again after high levels of exposure. We get the following pairs of scores: Low: 14 13 17 15 18 17 14 16 High: 18 12 20 19 22 19 19 16 a. State the null and alternative hypotheses. b. Using an alpha = 0.05, what is t (crit)? c. Using SPSS, calculate t (obu) (Use paired/related sample t test to obtain this info) d. What should you conclude?
2. Motor vehicle collision is one of major causes of death in North America. Although the causes of motor vehicle collisions are complicated, many believe that cellular telephones while driving may contribute to collisions by distracting drivers. In order to test the hypothesis that using a cellular telephone while driving increases the risk of a motor vehicle collision. An observational epidemiological study was proposed to assess the association. If you are the principal investigator of the project, a. What type of observational study would be ideal to study this hypothesis? b. Why do you recommend this study design?
5. In the United States, there is a strong relationship between education and smoking: well-educated people are less likely to smoke. Does a similar relationship hold in France? To find out, researchers recorded the level of education and smoking status of a random sample of 459 French men aged 20 to 60 years.36 The two-way table below displays the data. Is there convincing evidence of an association between smoking status and educational level among French men aged 20 to 60 years? Smoking Status Nonsmoker Former Moderate Heavy Primary School 56 54 41 36 Education Secondary School 37 43 27 32 University 53 28 36 16
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).
2. A researcher wants to determine which of three advertisements is most likely to encourage teens not to smoke. To assess the impact of each advertisement, she asks a sample of teenagers to view each ad and to rate the ad's effectiveness on a scale of 1 (not at all effective) to 7 (very effective). One ad used words only (no-cues condition), a second ad used a generic abstract picture (generic-cues condition), and a third showed a picture of a teen smoking and coughing (smoking-related cues condition). Fully test the question (5 steps) and determine the effect size. Participant ABCDEFG No Cues 2 3 1 4 4 5 2 T = 21 SS = 12 Generic Cues 5 5 4 5 3 4 2 T1 = 28 SS=8 Smoking- Related Cue 5 6 5 7 6 7 6 T2 = 42 SS = 4 P G = 91 ΣΧ2 = 451
3. Researchers Regine Dilla and associates wanted to determine whether consumption of cola is associated with lower bone mineral density. They looked at 1125 men and 1413 women in the Framingham Osteoporosis Study, which is a cohort that began in 1971. The first examination in this study began between 1971 and 1975, with participants returning for an examination every 4 years. Based on results of questionnaires, the researchers were able to determine cola consumption on a weekly basis. Analysis of the results indicated that women who consumed at least one cola per day (on average) had a bone mineral density that was significantly lower at the femoral neck than those who consumed less than one cola per day. The researchers did not find this relation in men. (a)Why is this a cohort study? (b)What is the response variable in this study? What is the explanatory variable? (c)Is the response variable qualitative or quantitative?
Suppose we are interested in the relationship between individuals’ place of residence (rural versus urban) and their political affiliation (Republican versus Democrat). A random sample of 100 individuals yields the following crosstabulation: Political Affiliation Place of Residence Republican Democrat Rural 21 29 Urban 14 36 a) In words, what is the null hypothesis to be tested? b) Is the relationship between place of residence and political affiliation statistically significant at the .05 level? (Be sure to show the statistics that lead to your decision.) c) Compute and interpret an appropriate measure of association for the relationship between these two variables.
3. A newly graduate of administration of justice has been hired by the regional director of the FBI to take a poll of a residential area to determine the proportion of residents who would be opposed to a gun exchange program in their community. The regional director of the FBI told her that if 50% or more of the residents are opposed to the idea, a gun exchange program will not be implemented. She takes a random sample of 150 household heads in the community and find that .42 of those sampled are opposed to the idea. Build a 99% confidence interval around this point estimate. Is 50% within her interval? What would she advise the regional director of the FBI who hired her?

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