Exercises 2:A clinical trial is run to assess the effectiveness of a new anti-retroviral therapy for patients with HIV. Patients arerandomized to receive a standard anti-retroviral therapy (usualcare) or the new anti-retroviral therapy and are monitored for3 months. The primary outcome is viral load which representsthe number of HIV copies per milliliter of blood. A total of 30participants are randomized and the data are shown below.Is there statistical evidence of a difference in viral load inpatients receiving the standard versus the new anti-retroviraltherapy?StandardTherapyNewTherapy7500 8000 2000 550 |1250 1000 2250 6800 3400 6300|9100|970 |1040|670 |400400 250 800 1400 8000 7400| 1020 6000 920 |1420| 2700 4200|5200|4100 undetectable

Answered: Image /qna-images/answer/c0e65c06-d6aa-41fe-b957-326a7f5e1f47.jpg

Answered: Exercises 2: A clinical trial is run to…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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Three different washing solutions are being compared to study their effectiveness in retarding bacteria growth in five-gallon milk containers. The analysis is done in a laboratory, and only three trials can be run on any day. Because days could represent a potential source of variability, the experimenter decides to use a randomized block design. Observations are taken for four days, and the data are shown here. Analyze the data from this experiment (use a = 0.05) and draw conclusions Days Solution 1 2 3 4 1 13 22 18 39 2 16 24 17 44 3 5 4 1 22
We often see players on the sidelines of a football game inhaling oxygen. Their coaches think this will speed their recovery. We might measure recovery from intense exertion as follows: Have a football player run 100 yards three times in quick succession. Then allow three minutes to rest before running 100 yards again. Time the ﬁnal run. Two experiments to investigate the eﬀect of inhaling oxygen during the rest period can be implemented. One of the experiments is to be a completely randomized design and the other is a matched pairs design in which each subject serves as his or her own control. Suppose you have twenty football players available as subjects. For both experiments, carry out the randomization of the twenty football players to treatments as required by the design. Use Table A to carry out the randomization in both a completely randomized comparative design and a matched pairs design. Starting at line 142, determine IDs for 10 football players from the first group.…
The Paleo diet allows only for foods that humans typically consumed over the last 2.5 million years, excluding those agriculture-type foods that arose during the last 10,000 years or so. Researchers randomly divided 500 volunteers into two equal-sized groups. One group spent 6 months on the Paleo diet. The other group received a pamphlet about controlling portion sizes. A randomized treatment assignment was performed, and at the beginning of the study, the average difference in weights between the two groups was about 0 pounds. After the study, the Paleo group had lost an average of 7.1 pounds with a standard deviation of 22.75 pounds while the control group had lost an average of 4.5 pounds with a standard deviation of 11.5 pounds. After failing to reject the null hypothesis support your answer with a p-value (a) P-value = _______
A new screening test for Lyme disease is developed for use in the general population. The sensitivity and specificity of the new test are 60% and 70%, respectively. Five hundred people are screened at a clinic during the first year the new test is implemented. Assume the true prevalence of Lyme disease among clinic attendees is 10%. Calculate the predictive value of a positive test.
Infectious Disease Commonly used vaccines for influenza are trivalent and contain only one type of influenza B virus. They may be ineffective against other types of influenza B virus. A randomized clinical trial was performed among children 3 to 8 years of age in 8 countries. Children received either a quadrivalent vaccine (QIV) that had more than one influenza B virus or a trivalent Hepatitis A vaccine (control). An attack rate (i.e.,% of children who developed influenza) starting 14 days after vaccination until the end of the study was computed for each vaccine group, stratified by age. The following data were reported. age QIV group 3-4 5-8 3.75 1.71 Control group 5.64 5.17 (a) Suppose 3 children in a village ages 3, 5, and 7 are vaccinated with the QIV vaccine. What is the probability that at least one child among the 3 will get influenza? (Round your answer to four decimal places.) (b) Suppose that 80% of 3-4-year-old children and 70% of 5-8-year-old children in a village are…
ester Hollar is vice president for human resources for a large manufacturing company. In recent years, he has noticed an increase in absenteeism that he thinks is related to the general health of the employees. Four years ago, in an attempt to improve the situation, he began a fitness program in which employees exercise during their lunch hour. To evaluate the program, he selected a random sample of eight participants and found the number of days each was absent in the six months before the exercise program began and in the six months following the exercise program. Below are the results. Employee Before After 1 6 5 2 6 2 3 7 1 4 7 3 5 4 3 6 3 6 7 5 3 8 6 7 At the 0.05 significance level, can he conclude that the number of absences has declined? Estimate the p-value. State the decision rule for 0.05 significance level. (Round your answer to 3 decimal places.) Compute the test statistic. (Round your answer to 3 decimal places.)
Data originally from DASL http://lib.stat.cmu.edu/DASL/Datafiles/CancerSurvival.html (Links to an external site.). Some bronchial cancer patients had the following survival times (in days) after receiving a certain treatment: 20, 37, 63, 64, 72, 81, 138, 151, 155, 166, 166, 223, 245, 246, 450, 459. (The second instance of “166” is not a mistake.) Do these numbers suggest that the average survival time, for all bronchial cancer patients who receive that treatment, is significantly different from 200 days? CANCER SURVIVAL Report an appropriate one-sample hypothesis test and use a 10% significance level. For Step 4 of the six-step process that was taught in this class, choose the BEST option to complete the following sentence: We assume that the sample of subjects is a SRS and we assume that the population of observations has no outliers ... and is Normally distributed. and is without a doubt bell-shaped. and is Uniformly distributed. (nothing needs to go here because the sample…
Data originally from DASL http://lib.stat.cmu.edu/DASL/Datafiles/CancerSurvival.html (Links to an external site.). Some bronchial cancer patients had the following survival times (in days) after receiving a certain treatment: 20, 37, 63, 64, 72, 81, 138, 151, 155, 166, 166, 223, 245, 246, 450, 459. (The second instance of “166” is not a mistake.) Do these numbers suggest that the average survival time, for all bronchial cancer patients who receive that treatment, is significantly different from 200 days? CANCER SURVIVAL Report an appropriate one-sample hypothesis test and use a 10% significance level. For Step 5 of the six-step process that was taught in this class, which would be the appropriate procedure and why? Choose the correct option. Group of answer choices We would do a t-procedure because we have the standard deviation. We would do a t-procedure because the sample size is large. We would do a t-procedure because we do not have the population standard deviation and…
A study was made of 1,057 cases of poisoning in children treated as inpatients at Milwaukee Children's Hospital from 1962 through 1968. Data on date of occurrence, age and sex of the child, and type of agent involved were recorded and analyzed by standard statistical methods. Poisoning was due to ingestion of aspirin in 35 per cent of the children studied and to the ingestion of hydrocarbon distillates in 18 per cent. A statistically significant male dominance was found for ingestion of hydrocarbons; age-specific peaks were found for some categories. Trends as to the relative and absolute frequencies of each specific poison from one year to the next were noted; possible reasons for increasing or decreasing trends are discussed. Is this study descriptive or inferential? Explain your answer. What are the variables used in the study? In your opinion, what level of measurement was used to obtain the data from the variables? Does the article define the population? If so, how is it…
A study in a journal published by the American Academy of Pediatrics (as reported in the Miami Herald, Jan. 14, 1997) seems to suggest that preschoolers who drink more than 12 ounces of fruit juice a day tend to be heavier and shorter than preschoolers who do not. The study involved a random sample of 168 healthy youngsters of whom 59 drank on average more than 12 ounces of fruit juice per day. Each child was weighed and measured. The measurements were then converted to percentage of normal height and weight for a child of that age and gender. For example, a weight percentage of 1.1 indicates that the child is 10% heavier than average. A recorded 0.80 indicates the child is 20% below the average. An average weight is recorded as 1.0. Same with height. Column 1: Juice 1- indicates child DID drink > 12 oz 2- child DID NOT drink > 12 oz Column 2: Weight% weight converted to percent of…
Denny studied factors affecting cardiovascular reactivity to a postural change in a sample of healthy men and women. Change in systolic blood pressure (SBP) from supine to standing position was used as the measure of cardiac reactivity in a sample of 842 adults. Supine measurement of blood pressure was taken after participants had lain on an examination table for 15 minutes. Blood pressure was determined every 30 seconds using a Dinamap device for 2 minutes, and the measurements were averaged. Participants then stood up immediately, and additional measurements were made for another 2 minutes. Below is a table describing the characteristics of Denny’s sample: Which measures of dispersion, if any, are presented in this table (Ranges, SDs)? If age is normally distributed, approximately what percent of the sample would be younger than 50? If BMI is normally distributed, approximately what percent of the sample would have a BMI higher than 33.1?
When only two treatments are involved, ANOVA and the Student’s t-test (Chapter 11) result in the same conclusions. Also, for computed test statistics, t2 = F. To demonstrate this relationship, use the following example. Fourteen randomly selected students enrolled in a history course were divided into two groups, one consisting of six students who took the course in the normal lecture format. The other group of eight students took the course in a distance format. At the end of the course, each group was examined with a 50-item test. The following is a list of the number correct for each of the two groups. Traditional Lecture Distance 36 45 31 35 40 45 34 35 33 45 38 36 43 41 a-1. Complete the ANOVA table. (Round your SS, MS, and F values to 2 decimal places and p-value, F crit to 4 decimal places.) Source of Variation SS df MS F p-value F crit Treatment 96.01 1 96.01 5.67 0.0350 Error 203.21 12 16.93 Total 299.21 13…

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