Concept explainers
Women diagnosed with breast cancer whose tumors have not spread may be faced with a decision between two surgical treatments—mastectomy (removal of the breast) or lumpectomy (only the tumor is removed). In a long-term study of the effectiveness of these two treatments, 701 women with breast cancer were randomly assigned to one of two treatment groups. One group received mastectomies and the other group received lumpectomies and radiation. Both groups were followed for 20 years after surgery. It was reported that there was no statistically significant difference in the proportion surviving for 20 years for the two treatments (Associated Press, October 17, 2002).
What hypotheses do you think the researchers tested in order to reach the given conclusion?
Want to see the full answer?
Check out a sample textbook solutionChapter 11 Solutions
Introduction to Statistics and Data Analysis
- What is meant by the sample space of an experiment?arrow_forwardList the sample space of each experiment. Tossing three coinsarrow_forwardIndividuals who have experienced a stroke are at an increased risk of having another stroke. Prevention is particularly important for high-risk populations. The Second European Stroke Prevention Study asked whether daily doses of an anti- blood-clotting agent, such as aspirin or dipyridamole, would help prevent strokes among patients who had just experienced a first stroke. Volunteer patients were randomly assigned to one of four treatment options: placebo, aspirin, Dipy., Both drugs. Researchers then recorded the patients who had another stroke and specifically if they died from that second stroke or not. Conduct the chi-square test of independence. What decision is made? Did not die from 2nd stroke 1447 1467 1466 1465 Died from 2nd stroke Placebo Aspirin Dipyr. Both drugs 202 182 188 185 Reject Ho. Fail to reject Ho.arrow_forward
- Researchers are interested in determining if there is a difference in the proportion of women who choose the different types of treatments for those diagnosed with Ductal Carcinoma in Situ (DIS) breast cancer, which is a form of breast cancer that occurs in the Breast Ducts and has not spread. Following a diagnoses of DCIS, women can choose between three different treatment plans: a mastectomy or a lumpectomy followed by radiation therapy or a lumpectomy followed by Adjuvant Endocrine therapy. A random sample of 500 women diagnosed with DCIS breast cancer was obtained. Of the 500 women, 190 chose to have a mastectomy, 150 chose to have a lumpectomy followed by radiation, and 160 chose to have a lumpectomy followed by Adjuvant Endocrine therapy. At the 1% significance level, what conclusion can be reached?arrow_forwardCocaine addiction is very hard to break. Even among addicts trying hard to break the addiction, relapse is common. (A relapse is when a person trying to break out of the addiction fails and uses cocaine again.) A study is conducted to investigate the effectiveness of two drugs, desipramine and lithium, in the treatment of cocaine addiction. The subjects in the six-week study were cocaine addicts seeking treatment. The 72 subjects were randomly assigned to one of three groups (desipramine, lithium, or a placebo, with 24 subjects in each group) and the study was double-blind. Relapse No relapse Desipramine 10 14 Lithium 18 6 Placebo 20 4 1.We are interested in knowing whether there was a difference in the proportion of relapse between the two drugs. Write the null and alternative hypotheses that would help determine an answer to our research their question. (You are writing equations, not words.) H0: HA: Define the symbol(s) you used in your…arrow_forwardIn a study of the adverse effects of x-rays among children, a retrospective cohort study was done using records from several large children's hospitals for the period of 1980 to 1985. 5,000 children were selected as a representative population of ill children seen at the hospitals during that time. Subjects were classified according to whether or not they received an x-ray during their stay in the hospital and were followed from their hospital stay through 2005 for the development of cancer. During the follow-up period, 30 incident cancers occurred in 3,000 children who had received an x-ray, and 5 incident cancers occurred in the 2,000 children who had not received an x-ray during their hospitalization. 1q. What are the rates of cancer incidence in each exposure group (per 1,000)? b.What is the attributable risk of cancer due to x-ray in this study population? 11c.. What is the risk ratio for the effect of exposure on the development of cancer in this study? What is the interpretation…arrow_forward
- A study is testing the effectiveness of a new allergy medication. Sixty people who reported they experience allergies were randomly assigned to one of two groups: one with the new medication, and another with a placebo. After two weeks, the subjects were surveyed by technicians to determine their level of allergic symptoms. Which of the following would benefit this experiment the most? A. This experiment should be double blind. Neither the subject nor the technician should know which group is receiving the new medication and which is receiving the placebo. This method would control for the placebo effect and prevent any effect on the response. B. This experiment should be single blind. The subjects do not know which treatment they are receiving to control for the placebo effect, but the technicians need to know which group received which treatment. C. This experiment should be single blind. The subjects know which treatment they are receiving but the technicians do not know which…arrow_forwardA study investigated the joint effects of sleep quality and sleep duration on the development of coronary heart disease (CHD). A total of 60,586 individuals aged 40 and older with no current or prior history of CHD were enrolled into the study. A self-administered questionnaire was used to collect information on sleep quality and duration at the start of the study, and 43,910 participants reported getting ³6 hours of sleep per day. Participants were followed for approximately 12 years, for a total of 152,000 person-years among those getting <6 hours sleep/day and 527,000 person-years among those getting ³6 hours sleep/day. Out of 2,740 participants who developed CHD throughout follow-up, 721 participants reported getting <6 hours of sleep per day at baseline. Question 10: What is the incidence rate of coronary heart disease among all participants in the study?arrow_forwardAccording to a study on the effects of smoking by pregnant women on rates of asthma in their children, for expectant mothers who smoke 20 cigarettes per day, 22.2% of their children developed asthma by the age of two in the US. A biology professor at a university would like to test if the percentage is different in another country. She randomly selects 319 women who only deliver one child and smoke 20 cigarettes per day during pregnancy in that country and finds that 82 of the children developed asthma by the age of two. In this hypothesis test, Do the hypothesis test. Use a level of significance of a = 0.05; Use the unrounded values in Excel to find the answers for #3 and #4 1. This is an example of 2. Find the standard error. 3. Find the z value. Question 10 V a hypothesis test.arrow_forward
- According to a study on the effects of smoking by pregnant women on rates of asthma in their children, for expectant mothers who smoke 20 cigarettes per day, 22.2% of their children developed asthma by the age of two in the US. A biology professor at a university would like to test if the percentage is different in another country. She randomly selects 319 women who only deliver one child and smoke 20 cigarettes per day during pregnancy in that country and finds that 82 of the children developed asthma by the age of two. In this hypothesis test, Do the hypothesis test. Use a level of significance of a = 0.05; Use the unrounded values in Excel to find the answers for #3 and #4 ✓a hypothesis test. 1. This is an example of 2. Find the standard error. - 3. Find the z value. 4. Find the p-value. 5. The biology professor should -- the null hypothesis.arrow_forwardThe drug X is marketed to help protect against male pattern baldness, and it also may protect against prostate cancer. A large sampleof healthy men over age 60 were randomly assigned to receive either a daily drug X pill or a placebo. The study lasted nine years and the men had annual check-ups and a biopsy at the end of the study. Prostate cancer was found in 815 of 4368 men taking drug X and in 1176 of the 4698 men taking a placebo. What kind of a study is this and what mesure of assocation (rd, rr, or) can be used and why?arrow_forwardA cancer researcher believes that there may be an increase in the life expectancy of women diagnosed with terminal breast cancer if they attend group therapy in addition to receiving medical treatment such as chemotherapy and radiation. The doctor selects 50 women with stage 4 breast cancer. Twenty-five of these women are randomly assigned to attend group therapy once per week during treatment. The remaining women do not receive group therapy. Survival time, in years, from diagnosis until death is measured for each woman. What hypothesis test should be used to test the doctor's claim? The results of the study are shown in the table below. Women in Therapy Women NOT in Therapy i = 3.8 s = 0.6 * = 2.0 s = 1.5 n = 25 n = 25 Two sample pooled t-test Two sample z-test Two sample paired t-test Two sample not pooled (Welch's) t-test A two sample nonparametric testarrow_forward
- Holt Mcdougal Larson Pre-algebra: Student Edition...AlgebraISBN:9780547587776Author:HOLT MCDOUGALPublisher:HOLT MCDOUGALCollege Algebra (MindTap Course List)AlgebraISBN:9781305652231Author:R. David Gustafson, Jeff HughesPublisher:Cengage LearningGlencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw Hill