A new drug is proposed to treat multiple sclerosis. For a study, four groups of peoplewith MS are formed: (1) a group of women who take the drug, (2) a group of womenwho don't take the drug, (3) a group of men who take the drug, and (4) a group of menwho don't take the drug.Is it possible that the drug is effective among women (a larger percentage of group 1improves than group 2), and the drug is effective among men (a larger percentage ofgroup 3 improves than group 4), but the drug is not effective for the whole studiedpopulation?If so, give a numerical example showing how this could happen. If not, explain why not.

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Answered: A new drug is proposed to treat…

Advanced Engineering Mathematics

10th Edition

ISBN:9780470458365

Author:Erwin Kreyszig

Publisher:Erwin Kreyszig

Chapter2: Second-order Linear Odes

Section: Chapter Questions

Problem 1RQ

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In a 2009 study, a team of researchers recruited 38 men and divided them randomly into two groups - treatment or control. The also recruited 38 women and they randomly placed half the participants into the treatment group and the other half into the control group. One group was given 25 grams of chia seeds twice a day, and the other was given a placebo. The subjects volunteered to be a part of the study. After 12 weeks, the scientists found no significant difference between the groups in appetite or weight loss. Which of the following is true. (i) This is an observational study (ii) Blinding is used in this study because subjects in the control group recieved a placebo, so that htey were blinded to the treatment they recieved. (iii) We can safely generalize the conclusion (that chia seeds have no significant effect on appetite or weight loss) from the participants to the population at large because randomization is used when assigning participatns to groups.
Suppose administrators at a large school district decide to institute mandatory study halls at their middle schools in an effort to boost their students' academic performance. After one year, a guidance counselor decides to test whether students' grade point averages (GPAs) have improved compared to the previous school year. The counselor selects a random sample of 40 eighth-graders from throughout the district who were also enrolled in the district for seventh grade. He records their GPAs for grades seven and eight, and for each student, calculates the difference between the two. The counselor's data is summarized in the given table. Variabledescription Samplemean Sample standarddeviation Standarderror estimate seventh grade GPA x¯= 2.64796 s=0.45763 SE=0.07236 eighth grade GPA x¯=2.78543 s=0.54764 SE=0.08659 difference (8th - 7th) x¯=0.13747 s=0.34586 SE=0.05469 The counselor plans to use this information to conduct a matched-pairs t‑test of the null hypothesis H0:μ=0…
2. A group of doctors at a specific hospital believes that the normal survival rate for patients with extensive burns will significantly increase with the use of new fluid plasma compresses. Before the new treatment, the survival rate for extensive burn patients at the hospital was about 40%. Using the new compresses, the hospital found that 48 out of 90 patients with extensive burns survived. Does this provide sufficient evidence for the hospital to try to market the new fluid plasma compresses to other hospitals? Answer this question using a = 0.05.
Scenario: A researcher wants to study the effects of childhood stress, genetics, and their interaction for predicting aggression in adults. The researcher recruited 40 subjects, 20 reported they had no childhood stress and 20 reported they experienced severe childhood stress. The researcher is specifically interested in looking at the MAOA gene, because different versions of this gene are linked to aggression. The researcher conducts a genetic test and finds that half of subjects in each group have a gene for low MAOA activity and the other half have the gene for high MAOA activity. The researchers have the subjects self-rate their aggressive behavior over the last 6 months. 1. Given the scenario above, what are the null and alternative hypotheses? 2. Experimental design:a. What are the independent and dependent variables in this study? b. How many levels of each independent variable are there? c. What type of factorial ANOVA is this?
You are interested in testing if there is a difference in weight-loss between 3 popular diet types; low calorie, low fat and low carb. Participants are randomly assigned one of the three groups or a control group. The control group will be told that are participating in a weight-loss study, but will not be following any particular diet. This is to study the placebo effect, weight-loss from just participating in the study. At the start of the study, each participant's weight is recorded in pounds. After 8 weeks they are weighed again, and the weight difference is recorded. A positive value represents a weight loss while a negative value represents a weight gain. Test at 5% significance. Round answers to 3 decimal places. Diet Type Low Calorie Low Calorie Low Calorie Low Calorie Low Calorie Low Fat Low Fat Low Fat Low Fat Low Fat Low Carb Low Carb Low Carb Low Carb Low Carb Control Control Control Control Control Pounds Lost 6.9 4.7 3.5 7.7 5.9 3.8 1.4 3.8 5.2 2 4.9 2.6 2.7 5.6 3.4 1.3…
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Borderline personality disorder (BPD) is a psychological illness marked by an ongoing pattern of varying moods, self-image, and behavior. A psychologist wants to evaluate the effectiveness of dialectical behavior therapy (DBT) on BPD in a two month study. The psychologist randomly selected 500 people who have BPD to participate in a study. The 500 participants were divided into two groups based on gender. The first group, contained 344 females, they were given medication along with DBT therapy. The second group were comprised of 156 males, they received medication alone. At the end of the two month study, the psychologist administered a standard test to evaluate the symptoms of BPD. It was found that the group that received the DBT therapy along with the medication had about the same level of improvement in symptoms as the group that received the medication alone. The psychologist concluded that there is no evidence that DBT therapy is effective at improving the symptoms of Borderline…
A pharmaceutical company is testing the effectiveness of its vaccine across two different age brackets. They take a sample and split the participants up into two separate groups. Group A consists of 44 people who are between ages 13 and 18. Group B consists of 58 people between ages 19 and 26. After being administered the vaccine, it was found that 37 people from group A were immune to the virus and 42 people from group B were immune. (this is the same situation from the previous daily) Why do we use the 'pooled proportion' instead of the null hypothesis in the denominator of the test statistic? At a 10% significance level, is there reason to believe there is a difference in vaccine efficacy between Group A and Group B? explain each step
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?
A journal reported a study examining the possible impact of air pollution on the weight of babies. Researchers found that 9% of 174 babies bom to mothers who were exposed to heavy doses of air pollution in a city were classified as having low birthweight. Only 5% of 2300 babies bom in another hospital in the city whose mothers had not been exposed to air pollution were similarly classified. Does this indicate a possibility that air pollution might be linked to a significantly higher proportion of low-weight babies? a) Test an appropriate hypothesis at a = 0.10 and state your condlusion. b) If you concluded there is a difference, estimate that difference with a confidence interval and interpret that interval in context. Identify the test statistic. (Round to two decimal places as needed.) Identify the P-value from the output of the hypothesis test. (Round to three decimal places as needed.) State the conclusion. Ho. There V sufficient evidence at the a = 0.10 level of significance to…
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A study published in JAMA in 2004 examined past results of other studies on bariatric surgery. Bariatric surgery is done to replace the size of the stomach in various ways. It is typically used on only obese patients, and one the traditional form of the surgery, gastric bypass has a 1% mortality (death) rate caused by surgery. However, in the studies reporting on the effects of the surgery on Type ll diabetes, 1417 of 1846 diabetic patients recovered completely from diabetes after surgery. These patients no longer need medication like insulin (which is injected into the skin) or pills to help manage blood sugar. In a study released a decade later, the percentage of patients who recover from diabetes has increased 80%. Using confidence intervals determine whether this is a significant change from the 2004 data. Use n=2000

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