Find the value of the test statistic and find the 5% critical value An observational study of Alzheimer's disease (AD) obtained data from 13 AD patients exhibitingmoderate dementia and selected a group of 10 control individuals without AD. AD is a progressiveneurodegenerative disease of the elderly and advancing age is known to be a primary risk factor in ADdiagnosis. Therefore, it was crucial for the study's credibility to examine whether the ages in the ADgroup might be significantly different than in the control group. The ages of the subjects in years aresummarized in the R Output below.VariablenAlzheimers 13Control10Mean79.9268.25sd6.8912.93Minimum77.0054.00Q1 Median Q379.25 87.00 92.2556.00 65.00 82.00Maximum93.0089.00We want to test if the average age in the Alzheimer's group is significantly different than the controlgroup.

Hypotheses: H0:μ1=μ2H1:μ1≠μ2 The null hypothesis states that there is no difference in mean age in…

Answered: An observational study of Alzheimer's…

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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In a recent study, young adults (18-25 years) were randomly assigned to one of two treatments to increase seat belt use. The intervention group received Safe Vehicle Engagement (SAVE) intervention, a 6-week automated interactive text message program, including weekly seat belt use queries with feedback and goal support to increase seat belt use. The control group received similar queries but no additional feedback. The primary objective is to assess whether there is an association between treatment (SAVE vs control) and self-report of always using a seat belt over the past 2 weeks at the 6-week follow-up. Below is the 2x2 table of treatment and primary endpoint. Always wearing a seat belt Not always wearing a seat belt SAVE Intervention 34 48 Control 15 61 Questions: (1) Estimate an appropriate absolute measure of association and 95% confidence interval (CI) comparing participants who received SAVE intervention to those who received control treatment. Be…
In a recent study, young adults (18-25 years) were randomly assigned to one of two treatments to increase seat belt use. The intervention group received Safe Vehicle Engagement (SAVE) intervention, a 6-week automated interactive text message program, including weekly seat belt use queries with feedback and goal support to increase seat belt use. The control group received similar queries but no additional feedback. The primary objective is to assess whether there is an association between treatment (SAVE vs control) and self-report of always using a seat belt over the past 2 weeks at the 6-week follow-up. Below is the 2x2 table of treatment and primary endpoint. Always wearing a seat belt Not always wearing a seat belt SAVE Intervention 34 48 Control 15 61 Questions: (1) Estimate an appropriate absolute measure of association and 95% confidence interval (CI) comparing participants who received SAVE intervention to those who received control treatment. Be…
A consumer advocacy group wanted to study whether different airline carriers differed in terms of their delayed flights. In particular, the researchers were interested in the relationship between p1, the proportion of Alpha Airlines flights that were delayed at least 15 minutes, and p2, the proportion of Beta Airlines flights that were delayed at least 15 minutes. A random sample of 1,000 Alpha flights and a separate random sample of 1,000 Beta flights found that 67 of the Alpha fights and 160 of the Beta flights were delayed at least 15 minutes. The conditions for inference were checked and verified. Does this set of samples provide strong evidence that Alpha Airlines has a smaller proportion of flights that are delayed at least 15 minutes than Beta Airlines, at the α = 0.05 significance level? Find the z-table here. A. The test statistic is z = –6.56 and the P-value ≈ 0. Since the P-value ≈ 0 < 0.05, there is not sufficient evidence that Alpha Airlines has fewer delayed…
What is the relative risk for the association between men and women vs COVID-19 infection? What do you conclude?
In a study, 28 adults with mild periodontal disease are assessed before and 6 months after implementation of a dental-education program intended to promote better oral hygiene. After 6 months, periodontal status improved in 15 patients, declined in 8, and remained the same in 5.9.1 Assess the impact of the program statistically (use a two-sided test).
The May 10, 2007 issue of The New England Journal of Medicine describes two large randomized, placebo-controlled trials of a vaccine for HPV-related cancer. HPV is human papillomavirus, the most common form of sexually transmitted infection. For the group of people who received the vaccine, the HPV-related cancer rate was much lower than for those who received a placebo. Which best describes the goal of this study?
Researchers were interested in comparing the long-term psychological effects on dieters who were on a high-carbohydrate, low-fat (LF) diet with those on a high-fat, low-carbohydrate (LC) diet. A total of 106 overweight and obese participants were randomly assigned to one of these two energy-restricted diets. At 52 weeks a total of 32 LC dieters and 33 LF dieters remained. Mood was assessed using a total mood disturbance score (TMDS), where a lower score is associated with a less negative mood. A summary of these results follows (image attached): (a) Is there a difference in the TMDS at Week 52? Test the null hypothesis that the dieters’ average mood in the two groups is the same. Use a significance level of 0.05. (b) Critics of this study focus on the specific LC diet (that is, the science) and the dropout rate. Explain why the dropout rate is important to consider when drawing conclusions from this study.
A case-control study is planned to investigate whether bottle-fed infants are at increased risk of death from acute respiratory infections compared breast-fed infants. The mothers of a group of cases (infants' deaths, with an underlying respiratory cause named on the death certificate) will be interviewed about the breast-feeding status of the child prior to the illness leading to death. The results will be compared to with those obtained from mothers of a group of healthy controls regarding the current breast-feeding status of their infants. It is expected that about 40% of controls will be bottle-fed, and we would like to detect a difference if bottle-feeding was associated with a two-fold increase of death (OR-2). A. How many cases and controls need to be studied to give a 90% power of achieving 5% significance level. Copy and paste/print the answer from the software. B. Repeat part (A) if the OR was three-fold increase. What do you notice about the sample size needed? Explain
A case−control study was performed among 145 subjects with macular degeneration and 34 controls, all of whom were 70- to 79-year-old women. A genetic risk score was developed to help differentiate the cases from the controls. The risk score was categorized into six groups (1, 2, 3, 4, 5, 6), with 6 being the highest risk and 1 being the lowest risk.The data in Table 10.48 were obtained relating the risk score to case/control status. taBlE 10.48 risk score cases controls 1 3 11 2 7 3 3 6 6 4 10 8 5 11 2 6 108 4 total 145 34 10.139 What test can be performed to study the asso- ciation between case/control status and risk score? Spe- cifically, we are interested in testing whether cases tend to have consistently higher risk scores or consistently lower risk scores than controls.
A 1980 study investigated the relationship between the use of OCs and the development of endometrial cancer. The researchers found that of 117 endometrial-cancer patients, 6 had used the OC Oracon at some time in their lives, whereas 8 of the 395 controls had used this agent. Test for an association between the use of Oracon and the incidence of endometrial cancer, using a two-tailed test.
A magazine reported on the "... treatment-emergent adverse events that occurred in 2% or more patients treated with a new medicine and with incidence greater than placebo in the treatment of depression, OCD, or bulimia." In the study, patients took the new medicine and patients were given placebo. Identify the a. treatment group, b. control group, and c. treatments.
Recently there has been quite a bit of controversy about the lack of definitive knowledge about the adverse side effects associated with hormone-based birth control usage. Suppose a researcher is interested in the effects of birth control in women aged 18-25 relevant to blood pressure. The researcher assumes that women in this demographic that are taking hormone-based birth control are at risk for increased blood pressure. Assume the following table contains the summary statistics of two SRSs, one from a cohort of women taking hormone-based birth control, and one from a cohort of women birth control free. Study Arm Average Systolic Blood Pressure (mmHG) Sample Standard Deviation Sample Size Birth Control 124 6.8 246 No Birth Control 116 4.3 267 Carry out the appropriate statistical procedure to determine if there is a significant difference in the systolic blood pressure between the two groups of women. Write out your null and alternative…

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