b) Same conclusion.

Question

asked 2021-05-05

\(\begin{array}{|c|c|} \hline Varieties & Location 1& Location 2& Location 3& Location 4& Location 5& Location 6 \\ \hline A& 35.3& 31.0& 32.7& 36.8& 37.2& 33.1 \\ \hline B& 30.7& 32.2& 31.4& 31.7& 35.0& 32.7\\ \hline C& 38.2& 33.4& 33.6& 37.1& 37.3& 38.2\\ \hline D& 34.9& 36.1& 35.2& 38.3& 40.2& 36.0\\ \hline E& 32.4& 28.9& 29.2& 30.7& 33.9& 32.1\\ \hline \end{array}\)

a. Use the appropriate nonparametric test to determine whether the data provide sufficient evidence to indicate a difference in the yields for the five different varieties of wheat. Test using \(\alpha\alpha=.05\).

b. How do the analysis of variance F test compare with the test in part a? Explain.

asked 2020-11-26

Use either the critical-value approach or the P-value approach to perform the required hypothesis test. For several years, evidence had been mounting that folic acid reduces major birth defects. A. Czeizel and I. Dudas of the National Institute of Hygiene in Budapest directed a study that provided the strongest evidence to date. Their results were published in the paper “Prevention of the First Occurrence of Neural-Tube Defects by Periconceptional Vitamin Supplementation” (New England Journal of Medicine, Vol. 327(26), p. 1832). For the study, the doctors enrolled women prior to conception and divided them randomly into two groups. One group, consisting of 2701 women, took daily multivitamins containing 0.8 mg of folic acid, the other group, consisting of 2052 women, received only trace elements. Major birth defects occurred in 35 cases when the women took folic acid and in 47 cases when the women did not. a. At the 1% significance level, do the data provide sufficient evidence to conclude that women who take folic acid are at lesser risk of having children with major birth defects? b. Is this study a designed experiment or an observational study? Explain your answer. c. In view of your answers to parts (a) and (b), could you reasonably conclude that taking folic acid causes a reduction in major birth defects? Explain your answer.

asked 2021-03-06

Use either the critical-value approach or the P-value approach to perform the required hypothesis test. Approximately 450,000 vasectomies are performed each year in the United States. In this surgical procedure for contraception, the tube carrying sperm from the testicles is cut and tied. Several studies have been conducted to analyze the relationship between vasectomies and prostate cancer. The results of one such study by E. Giovannucci et al. appeared in the paper “A Retrospective Cohort Study of Vasectomy and Prostate Cancer in U.S. Men” (Journal of the American Medical Association, Vol. 269(7), pp. 878-882). Of 21,300 men who had not had a vasectomy, 69 were found to have prostate cancer, of 22,000 men who had had a vasectomy, 113 were found to have prostate cancer. a. At the 1% significance level, do the data provide sufficient evidence to conclude that men who have had a vasectomy are at greater risk of having prostate cancer? b. Is this study a designed experiment or an observational study? Explain your answer. c. In view of your answers to parts (a) and (b), could you reasonably conclude that having a vasectomy causes an increased risk of prostate cancer? Explain your answer.

asked 2020-11-08

Replacement of paint on highways and streets represents a large investment of funds by state and local governments each year. A new, cheaper brand of paint is tested for durability after one month’s time by reflectometer readings. For the new brand to be acceptable, it must have a mean reflectometer reading greater than 19.6. The sample data, based on 35 randomly selected readings, show \(x =19.8\ and\ s=1.5\). Do the sample data provide sufficient evidence to conclude that the new brand is acceptable? Conduct hypothesis test using \(a=.05\). Use the traditional approach and the p-value approach to hypothesis testing! Show all of the steps of the hypothesis test for each approach.