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Angioplasty’s benefits challenged. More than 1 million heart patients each year undergo an angioplasty. The benefits of an angioplasty were challenged in a study of 2,287 patients (2007 Annual Conference of the American College of Cardiology. New Orleans). All the patients had substantial blockage of the arteries but were medically stable. All were treated with medication such as aspirin and beta-blockers However, half the patients were randomly assigned to get an angioplasty and half were not After 5 years, the researchers found that 211 of the 1,145 patients in the angioplasty group had subsequent heart attacks compared with 202 of 1,142 patients in the medication-only group Do you agree with the study’s conclusion. “There was no significant difference in the rate of heart attacks for the two groups”? Support your answer with a 95% confidence interval.
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- Red Wine and Weight LossResveratrol, a compound in grapes and red wine, has been shown to promote weight loss in rodents and now in a primate.1 Lemurs fed a resveratrol supplement for four weeks had decreased food intake, increased metabolic rate, and a reduction in seasonal body-mass gain compared to a control group. Suppose a hypothetical study is done for a different primate species, with one group given a resveratrol supplement and the other group given a placebo. We wish to see if there is evidence that resveratrol increases the mean metabolism rate for this species. (This exercise presents hypothetical data. We will see the results from the actual study later in this chapter.) (a) State the null and alternative hypotheses.Let group 1 be the species taking a resveratrol supplement and let group 2 be the species taking a placebo.arrow_forwardThe Diabetes Control and Complications trial research group, randomly assigned volunteers with type 1 (insulin-dependent) diabetes mellitus, but without retinopathy, either to a conventional treatment or to a more intensive treatment aimed at maintaining normal blood glucose levels. The volunteers' health was monitored closely for approximately six years. By the end of the study, 91 patients out of 378 in the conventional treatment group had developed retinopathy, whereas 23 out of 348 in the intensive treatment group had developed retinopathy. Test whether the rates of retinopathy differed significantly between the two treatment groups, if they did, which rate was significantly lower. 1. Provide the null hypothesis 2. Provide the alternative hypotheses 3. calculate the appropriate test statistic. Show all work 4. Identify the p-value for that test statistic 5. Using the p-value method and an alpha level of 0.02 state what your conclusions are regarding the null hypothesis, and…arrow_forwardThe Diabetes Control and Complications trial research group, randomly assigned volunteers with type 1 (insulin-dependent) diabetes mellitus, but without retinopathy, either to a conventional treatment or to a more intensive treatment aimed at maintaining normal blood glucose levels. The volunteers' health was monitored closely for approximately six years. By the end of the study, 91 patients out of 378 in the conventional treatment group had developed retinopathy, whereas 23 out of 348 in the intensive treatment group had developed retinopathy. Test wether the rates of retionpathy differed significantly betweenthe two treatment groups, if they did, which rate was significantly lower. 1. Provide the null hypothesis 2. Provide the alternative hypotheses 3. calculate the appropriate test statistic. Show all work 4. Indentify the p-value for that test statistic 5. Using the p-vlaue method and an alpha level of 0.02 state what your conclusions is regarding the null hypothesis, and…arrow_forward
- Sleep apnea is a disorder characterized by pauses in breathing during sleep. Children who suffer from untreated sleep apnea often have behavior problems, including hyperactivity, inattention, and aggression. A common treatment for pediatric sleep apnea is the surgical removal of enlarged tonsils and adenoids that are obstructing the airways. Suppose researchers at a sleep clinic are interested in the effect of surgical treatment for pediatric sleep apnea on aggressive behavior. They study 11 children without sleep apnea, 11 children with untreated sleep apnea, and 11 children who have been surgically treated for sleep apnea. Aggression is measured using the Conners Rating Scales. The sample means and sums of squares of the scores for each of the three groups are presented in the following table. Group Sample Mean Sum of Squares No Sleep Apnea 0.59 0.3240 Untreated Sleep Apnea 0.45 0.4410 Treated Sleep Apnea 0.31 0.2250 The researchers perform an analysis of…arrow_forwardA clinical trial was conducted among 178 patients with advanced melanoma (a type of skin cancer). There were two treatment groups. Group A received Interleukin-2. Group B received Interleukin-2 plus a vaccine. Six percent of Group A patients and 17% of group B patients had a complete or partial response to treatment. One issue is that some patients experience side effects and have to discontinue treatment. It was estimated that 21% of patients receiving Interleukin-2 plus a vaccine developed an arrhythmia (irregular heartbeat) and had to discontinue treatment. Since the side effect was attributable to the vaccine, assume that the patients would continue to take Interleukin-2 if arrhythmia developed but not the vaccine and that the probability of a positive response to the treatment would be the same as group A (i.e., 6%)Suppose we have 10 patients who receive Interleukin-2 plus vaccine of whom 2 develop arrhythmia and 8 do not. What is the probability that exactly 2 of the 10 patients…arrow_forwardA psychologist conducts a 2 x 3 x 2 ANOVA. How many main effects are possible? How many interactions are possible?arrow_forward
- A pharmaceutical company is developing a new drug to treat a certain medical condition. The company has conducted a clinical trial to test the efficacy of the drug. The trial included 200 patients, half of whom were randomly assigned to receive the new drug and half of whom were randomly assigned to receive a placebo. At the end of the trial, 50% of the patients who received the new drug showed improvement, compared to only 30% of the patients who received the placebo. Test the hypothesis that the new drug is more effective than the placebo using a significance level of 0.01. Also, calculate the p-value and the 95% confidence interval for the difference in proportions between the two groups.arrow_forwardQuestion Red Wine and Weight LossResveratrol, a compound in grapes and red wine, has been shown to promote weight loss in rodents and now in a primate.1 Lemurs fed a resveratrol supplement for four weeks had decreased food intake, increased metabolic rate, and a reduction in seasonal body-mass gain compared to a control group. Suppose a hypothetical study is done for a different primate species, with one group given a resveratrol supplement and the other group given a placebo. We wish to see if there is evidence that resveratrol increases the mean metabolism rate for this species. (This exercise presents hypothetical data. We will see the results from the actual study later in this chapter.) (a) State the null and alternative hypotheses.Let group 1 be the species taking a resveratrol supplement and let group 2 be the species taking a placebo.arrow_forwardDoes posting calorie content for menu items affectpeople’s choices in fast-food restaurants? According to results obtained by Elbel, Gyamfi, and Kersh(2011), the answer is no. The researchers monitoredthe calorie content of food purchases for children andadolescents in four large fast-food chains before andafter mandatory labeling began in New York City. Although most of the adolescents reported noticing thecalorie labels, apparently the labels had no effect ontheir choices. Data similar to the results obtained showan average of M = 786 calories per meal with s =85 for n =100 children and adolescents before thelabeling, compared to an average of M = 772 calorieswith s = 91 for a similar sample of n = 100 after themandatory posting.a. Use a two-tailed test with a = .05 to determinewhether the mean number of calories after theposting is significantly different than before caloriecontent was posted.b. Calculate r2to measure effect size for the mean difference.arrow_forward
- Trichotillomania is an illness characterized by the repeated urge to tear out hair, eyelashes, facial hair, nose hair, pubic hair, eyebrows, or other body hair, sometimes resulting in noticeable bald patches. A pharmaceutical company is trying to decide whether to market a drug to treat trichotillomania. The pharmacist who designed the drug believes it is very effective, especially when combined with therapy, whereas a researcher who did research on a sample of people suffering from the disorder is less convinced. Each of them created graphs to support his or her position. Determine whether the pharmacist or the researcher created each graph. (Hint: Decide whether the graph minimizes or maximizes the effect of the drug first. Then decide who would want to do that, and choose your response from the list of possible combinations.)arrow_forwardA psychologist develops an intervention designed to reduce test anxiety associated with taking the SAT. The psychologist claims that reduced test anxiety will lead to higher scores on the quantitative section of the SAT. Because she believes all students experience some degree of anxiety related to the SAT, she further claims her intervention should work for all students, not just those who report abnormal levels of test anxiety. She randomly selects 30 high school juniors, and with the consent of their parents, delivers her intervention. Subsequently, these students take the SAT, and she collects their scores. The quantitative section of the SAT has a mean of 500 and a standard deviation of 100 in the general population, and scores are normally distributed. a. What type of test should be used to analyze her data? i. Z-test ii. Single-sample t-test iii. Independent-measures t-test iv. Repeated-measures t-test b. What would the hypotheses be?arrow_forwardA test of body reaction to the Malaysian citizens who have taken their vaccine was conducted. Selected citizens who got side effect are categorised according to their blood type and the type of vaccine received. From a sample of 250 citizens, 150 of them were administered with Sinovac while the rest received AstraZeneca. Table 4 shows the number of citizens who had side effect after being vaccinated. Type of vaccine Blood type A B AB O Sinovac 50 M 50 20 AstraZeneca 30 20 20 N Does different blood type among people who had side effect relate to the type of vaccinereceived at A=0.025?arrow_forward
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