In a double-blind experiment designed to test the effectiveness of a newmedication as a treatment for lower back pain, 1643 patients were randomlyassigned to one of three groups: (1) the 547 subjects in the placebo group weregiven pills containing no medication; (2) 550 subjects were in a group given pillswith the new medication taken at regular intervals; (3) 546 subjects were in a groupgiven pills with the new medication to be taken when needed for pain relief.What does it mean to say that the experiment was "double-blind"?Choose the correct answer below.O A. The subjects in the study were given the choice of taking the placebo orthe new medication, but those who administered the pills did not knowwhich group the subjects were in.B. The subjects in the study did not know whether they were taking aplacebo or the new medication, but those who administered the pills didknow.OC. The subjects in the study did not know whether they were taking aplacebo or the new medication, and those who administered the pills alsodid not know.O D. Both the subjects in the study and those who administered the pills knewwhether they were taking a placebo or the new medication.Next Determine whether the given value is a statistic or a parameter.A survey found that 86% of all respondents were optimistic.Choose the correct answer below.O A. The value is a parameter because it is a numerical measurementdescribing some characteristic of a population.O B. The value is a parameter because it is a numerical measurementdescribing some characteristic of a sample.OC. The value is a statistic because it is a numerical measurement describingsome characteristic of a population.O D. The value is a statistic because it is a numerical measurement describingsome characteristic of a sample.Next

Double blind experiment - Neither patient nor researcher knows which treatments are receiving until…

Answered: In a double-blind experiment designed…

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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A psychologist has developed a mental alertness test. She wishes to study the effects (if any) of type of food consumed on mental alertness. Twenty-one volunteers were randomly divided into two groups. Both groups were told to eat the amount they usually eat for lunch at noon. At 2:00 P.M., all subjects were given the alertness test. Group A had a low-fat lunch with no red meat, lots of vegetables, carbohydrates, and fiber. Group B had a high-fat lunch with red meat, vegetable oils, and low fiber. The only drink for both groups was water. The test scores are shown below. Group A 67 93 82 69 76 47 43 58 92 63 52 Group B 70 57 75 59 66 49 55 46 45 91 89 72 Use a 10% level of significance to test the claim that there is no difference in mental alertness distributions based on type of lunch. (a) What is the level of significance? (b) Compute the sample test statistic. (Use 2 decimal places.) (c) Find the P-value of the sample test statistic. (Use 4 decimal places.)
Sigall and Ostrove (1975) did an experiment to assess whether the physical attractiveness of a defendant on trial for a crime had an effect on the severity of the sentence given in a mock jury trials. Each of the participants in this study was randomly assigned to one of the following three treatment groups; every participant received a package that described a burglary and gave background information about the accused person. The three treatment groups differed in the type of information that they were given about the accused person’s appearance. Members of Group 1 were showing a photo of an attractive person; members of Group 2 were shown a photograph of an unattractive person; members of Group 3 saw no photograph. Some of their results are described here. Each participant was asked to assign a sentence (in years) to the accused person; the researchers predicted that more attractive persons would receive shorter sentences. a)Prior to assessment of the outcome, the researchers did a…
The NIH is funding a trial for a new antidepressant drug. A sample of 1000 people with severe depression are recruited and, at baseline, are given a questionnaire asking about their demographic characteristicsand their mental health. They are then randomly assigned to one of two groups. The treatment group receives the new antidepressant, a pill that must be taken twice a day. The control group receives a placebo pill containing nothing medically active, which must also be taken twice a day. After 10 weeks, researchers locate the individuals and ask them to fill out a questionnaire again assessing their mental health. At the end of the study, researchers find no statistically significant difference in the mental health of the treatment and control groups. Q: Should we be concerned about unbalanced groups here? Is it possible to empirically explore whether this is a problem for this study?
Researchers investigate how the presence of cell phones influence the quality of human interaction. Subjects are randomly selected from a population and divided into an experimental group that is asked to leave their phones in the front of the room and a control group that are not asked to leave their cell phones at the front of the room. Subjects are left alone for 10 minutes and then asked to take a survey designed to measure quality of interactions they had with others in the experiment. What statistical test is appropriate?
Trichotillomania is a psychiatric illness that causes its victims to have an irresistible compulsion to pull their own hair. Two drugs were compared as treatments for trichotillomania in a study involving 13 women. Each women took clomipramine during one time period and desipramine during another time period in a double-blind experiment. Scores on a trichotillomania-impairment scale, in which high scores indicate greater impairment, were measured on each women during time period. The average of the 13 measurements for clomipramine was 6.2; the average of the 13 measurements for desipramine as 4.2. (a) A paired t test was used to test whether the mean difference between these two drugs is 0, resulting in a test statistics t∗ = 2.47. Find the sample standard deviation Sd. (b) Find a 95% confidence interval for the mean difference between the two drugs and give the conclusion.
Migraine and Acupuncture: A migraine is a particularly painful type of headache, which patients sometimes wish to treat with acupuncture. To determine whether acupuncture relieves migraine pain, researchers conducted a randomized controlled study where 88 females diagnosed with migraine headaches were randomly assigned to one of two groups: treatment or control. 54 patients in the treatment group received acupuncture that is specifically designed to treat migraines. 34 patients in the control group received placebo acupuncture (needle insertion at non-acupoint locations). 24 hours after patients received acupuncture, they were asked if they were pain free. Results are summarized in the contingency table below. (please round answers to within one hundredth of a percent) Pain Free: Yes Pain Free: No Total Treatment 10 44 54 Control 3 31 34 Total 13 75 88 a) What percent of patients in the treatment group were pain free 24 hours after receiving acupuncture? b) What…
In randomized, double-blind clinical trials of a new vaccine, children were randomly divided into two groups. Subjects in group 1 received the new vaccine while subjects in group 2 received a control vaccine. After the second dose, 125 of 746 subjects in the experimental group (group 1) experienced fever as a side effect. After the second dose, 82 of 627 of the subjects in the control group (group 2) experienced fever as a side effect. Does the evidence suggest that a higher proportion of subjects in group 1 experienced fever as a side effect than subjects in group 2 at the a= 0.01 level of significance? Find the test statistic for this hypothesis test. (Round to two decimal places as needed.)
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
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.)
In a study on the effect of an oral rinse on plaque buildup on teeth, sixteen people whose teeth were thoroughly cleaned and polished were randomly assigned to two groups of eight subjects each. Both groups were assigned to use oral rinses (no brushing) for a 2-week period. Group 1 used a rinse that contained an antiplaque agent. Group 2, the control group, received a similar rinse except that the rinse contained no antiplaque agent. A measure of plaque buildup was recorded at 14 days with means and standard deviations for the two groups shown in the table. Control Group Antiplaque Group Sample Size 8 8. Mean 1.22 0.77 Standard Deviation 0.33 0.33 n USE SALT (a) State the null and alternative hypotheses that should be used to test the effectiveness of the antiplaque oral rinse. O Ho: (H, - H2) = 0 versus H: (, - H2) 0 O Ho: (H1 - H2) = 0 versus H,: (H, - H2) > 0 O Ho: (H1 - H2) = 0 versus H.: (4, - H2) # 0 (b) Do the data provide sufficient evidence to indicate that the oral…
In randomized, double-blind clinical trials of a new vaccine, monkeys were randomly divided into two groups. Subjects in group 1 received the new vaccine while subjects in group 2 received a control vaccine. After the second dose, 117 of 750 subjects in the experimental group (group 1) experienced drowsiness as a side effect. After the second dose, 74 of 631 of the subjects in the control group (group 2) experienced drowsiness as a side effect. Does the evidence suggest that a higher proportion of subjects in group 1 experienced drowsiness as a side effect than subjects in group 2 at the a = 0.05 level of significance? Determine the P-value for this hypothesis test. (Round to three decimal places as needed.) Interpret the P-value. If the population proportions are one would expect a sample difference proportion the one observed in about out of 1000 repetitions of this experiment. (Round to the nearest integer as needed.) State the conclusion for this hypothesis test. A. Reject Ho.…
Migraine and Acupuncture: A migraine is a particularly painful type of headache, which patients sometimes wish to treat with acupuncture. To determine whether acupuncture relieves migraine pain, researchers conducted a randomized controlled study where patients diagnosed with migraine headaches were randomly assigned to one of two groups: treatment or control.Patients in the treatment group received acupuncture that is specifically designed to treat migraines and patients in the control group received placebo acupuncture (needle insertion at non-acupoint locations). 24 hours after patients received acupuncture, they were asked if they were pain free. Results are summarized in the contingency table below. Test to see if migraine pain relief is dependent on receiving acupuncture. Test at the 8% level and round expected values to one decimal place. Pain Relief Yes (Observed) Yes (Expected Value) No (Observed) No (Expected Value) Row Total No Relief 29 29 58 Control 91 103…

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