Cheating: According to a report on academic cheating by ETS, the Educational Tes
ID: 3176526 • Letter: C
Question
Cheating: According to a report on academic cheating by ETS, the Educational Testing Service, college students majoring in Business and Engineering are more likely to cheat than students in other majors. For a statistics project, a community college student at Diablo Valley College decides to investigate cheating in two popular majors at DVC: business and nursing. She convinces professors who teach business and nursing courses to distribute a short anonymous survey in their classes. The question about cheating is one of many other questions about college life. From this data, the student plans to calculate a confidence interval for the difference in two population proportions. Which is the most reasonable description of the two populations for her conclusion? A) business and nursing students in the classes that were surveyed B) business and nursing students at DVC C) business and nursing students at community colleges D) business and nursing students at community colleges the year of the study Flag this Question Question 2 1 pts Cheating: For a statistics project a community college student at Diablo Valley College decides to investigate cheating in two popular majors at DVC: business and nursing. She selects a random sample of nursing and business courses and convinces the professors to distribute a short anonymous survey in their classes. The question about cheating is one of many other questions about college life. When the student summarizes the data, she finds that 42 of the 50 business students and 38 of the 70 nursing students admitted to cheating in their courses. Can the student proceed with the calculation of the confidence interval for the difference in population proportions? A) Yes, the counts suggest that the normal model is a good fit for the sampling distribution of sample differences. B) No, the counts do not suggest that the normal model is a good fit for the sampling distribution of sample differences. C) It is impossible to tell if the conditions are met with the information given. Flag this Question Question 3 1 pts Quit Smoking: Previous studies suggest that use of nicotine-replacement therapies and antipressants can help people stop smoking. The New England Journal of Medicine published the results of a double-blind, placebo-controlled experiment to study the effect of nicotine patches and the anti-depressant bupropion on quitting smoking. The target for quitting smoking was the 8th day of the experiment. In this experiment researchers randomly assigned smokers to treatments. Of the 160 smokers taking a placebo, 25 stopped smoking by the 8th day. Of the 244 smokers taking only the antidepressant buproprion, 74 stopped smoking by the 8th day. Calculate the 99% confidence interval to estimate the treatment effect of buproprion. (The standard error is about 0.041.) A) (0.078, 0.214) B) (0.067, 0.227) C) (0.041, 0.253) Flag this Question Question 4 1 pts In the context of the previous problem, what does “99% confident” mean? A) If we repeat this experiment many times, there is a 99% chance that the true treatment effect of buproprion will be in the 99% interval reported in the previous problem. B) There is a 99% chance that you correctly calculated the confidence interval in the previous problem. C) There is a 99% chance that the buproprion treatment is effective. D) If we repeat this experiment many times and calculate a 99% confidence interval each time, 99% of these confidence intervals will contain the true treatment effect. Flag this Question Question 5 1 pts Quit Smoking: The New England Journal of Medicine published the results of a double-blind, placebo-controlled experiment to study the effect of nicotine patches and the anti-depressant bupropion on quitting smoking. With the data from the experiment we calculate the sample difference in the “quit smoking” rates for the nicotine treatment group and the placebo group (“treatment” minus “placebo”). We get 0.8% = 0.008. What does the 0.008 tell us? A) In this experiment the nicotine treatment had a higher success rate, but the improvement was less than 1%. B) In this experiment, the placebo group had a higher success rate by 0.8%. C) Nicotine patches will produce a slightly higher success rate when compared to a placebo, but the difference is not statistically significant. Flag this Question Question 6 2 pts Quit Smoking: The New England Journal of Medicine published the results of a double-blind, placebo-controlled experiment to study the effect of nicotine patches and the anti-depressant bupropion on quitting smoking. With the data from the experiment we calculate the sample difference in the “quit smoking” rates for the nicotine treatment group and the placebo group (“treatment” minus “placebo”). We get 0.8% = 0.008. The 99% confidence interval based on this sample difference is -0.104 to 0.088. Mark each conclusion as valid or invalid. We are 99% confident that the proportion of smokers who will quit smoking with a nicotine patch treatment is about 8.8 to 10.4% higher than the proportion who quit smoking with a placebo treatment. The nicotine patch treatment is not effective in helping smokers quit. We are 99% confident that smokers using a nicotine patch treatment have a “quit smoking” rate that is anywhere from 10.4% lower to 8.8% higher than the success rate of smokers with a placebo treatment.
Explanation / Answer
Question 1Cheating:
Answer:
C) business and nursing students at community colleges
This is because only these two majors are of concern in community college
Question 2
B) No, the counts do not suggest that the normal model is a good fit for the sampling distribution of sample differences.
This is because n1*(1-p1)=50*(1-42/50)=8<10.
Question 3
C) (0.041, 0.253)
P1=25/160= 0.1563
P2=74/244=0.3033
P2-p1=0.1470
Critical z=2.576
Standard deviation SD= sqrt(p1*(1-p1)/n1+p2*(1-p2)/n2))
=sqrt(0.1563*(1-0.1563)/160+0.3033*(1-0.3033)/244))
=0.041
Margin of error E =( Critical z)*SD=2.576*0.041=0.106
99%cofndienc interval =(p2-p1)-E ,(p2-p1)+E
=0.147-0.106 , 0.147+0.106
=(0.041 0.253)
Question 4 1 By definition of confidence interval we have
D) If we repeat this experiment many times and calculate a 99% confidence interval each time, 99% of these confidence intervals will contain the true treatment effect.
Question 5 1
B) In this experiment, the placebo group had a higher success rate by 0.8%.
Question 6
Invalid----We are 99% confident that the proportion of smokers who will quit smoking with a nicotine patch treatment is about 8.8 to 10.4% higher than the proportion who quit smoking with a placebo treatment.
Valid-----The nicotine patch treatment is not effective in helping smokers quit.
Invalid---We are 99% confident that smokers using a nicotine patch treatment have a “quit smoking” rate that is anywhere from 10.4% lower to 8.8% higher than the success rate of smokers with a placebo treatment.