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…

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018

18th Edition

ISBN:9780079039897

Author:Carter

Publisher:Carter

Chapter4: Equations Of Linear Functions

Section: Chapter Questions

Problem 8SGR

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What is an experiment?
As men age, their testosterone levels gradually decrease. This may cause a reduction in energy, an increase in fat, and other undesirable changes. Do testosterone supplements reverse some of these effects? A study in the Netherlands assigned 237 men aged 60 to 80 with low or low-normal testosterone levels to either a testosterone supplement or a placebo. Why is it necessary to include a control group in this experiment? Every experiment needs a control group in order to make proper comparisons between treatments. A control group is necessary to balance the effects of other variables among the treatment groups. A control group is necessary so any differences in the effects of the treatments can be distinguished from chance differences between the groups. A control group helps avoid confounding and reduces variability in the response variable. A control group is used to provide a baseline for comparing the effects of other treatments.
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 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…
In 1990, 58% of Americans 18 years old and older reported they have a great deal of concern regarding air pollution. A recent poll found that 592 of 1004 Americans 18 years old or older stated that they have a great deal of concern regarding the level of air pollution in American. Is there evidence to conclude that the current proportion of Americans having a great deal of concern about the level of air pollution in America is different from the 1990 proportion, with a 10% level of significance? State the null hypothesis, alternative hypothesis, test statistic, p-value and conclusion.
There is growing concern over a possible causal link between consumption of diet soda and obesity. Gallup took in 2013 a nationally representative sample of 2027 adults and asked them about their soda consumption. In the sample, 921 adults described themselves as overweight, and 295 of them said that they mostly drink diet soda. The remaining 1106 adults described themselves as about right weight, and 210 of them said that they mostly drink diet soda. Is there evidence at 1% level that the proportions of adults who mostly drink diet soda with overweight and with about right weight are different? Which method will you use to perform the test? Choose the correct one. 1-sample T test 2-sample T test 2-sample Z test. 2-proportion Z test What is the pooled proportion? State the null and alternative hypotheses: Which distribution will you use for your test? Give the test statistic: Find the p-value: Decision and Conclusion:
McAllister et al. (2012) compared varsity football and hockey players with varsity athletes from noncontact sports to determine whether exposure to head impacts during one season have an effect on cognitive performance. In the study, tests of new learning performance were significantly poorer for the contact sport athletes compared to the noncontact sport athletes. The following table presents data similar to the results obtained in the study. Noncontact Athletes: 10, 8, 7, 9, 13, 7, 6, 12 Contact Athletes: 7, 4, 9, 3, 7, 6, 10, 2 a. Are the test scores significantly lower for the contact sport athletes than for the noncontact athletes? Use a one-tailed test with =.05 t-critical= t= b. Compute the value of (percentage of variance accounted for) for these data. r^2= a. 0.123, b. 0.239, c. 0.138, d. 0.264
McAllister et al. (2012) compared varsity football and hockey players with varsity athletes from noncontact sports to determine whether exposure to head impacts during one season have an effect on cognitive performance. In the study, tests of new learning performance were significantly poorer for the contact sport athletes compared to the noncontact sport athletes. The following table presents data similar to the results obtained in the study. Noncontact Athletes: 10, 8, 7, 9, 13, 7, 6, 12 Contact Athletes: 7, 4, 9, 3, 7, 6, 10, 2 a. Are the test scores significantly lower for the contact sport athletes than for the noncontact athletes? Use a two-tailed test with =.05 b. What sampling technique was most likely employed by the researcher? justify your answer c. Does exposure to head impacts have an effect on cognitive performance? why or why not
The Framingham Heart Study was a longitudinal cohort study of 5000+ men and women. One outcome of interest was fasting glucose levels. Glucose levels were categorized into three different categories: Glucose Levels -Diabetes (glucose > 126), -Impaired Fasting Glucose (glucose 100-125), -Normal Glucose Several possible risk factors were also recorded: Risk Factors -Sex -Age -BMI (normal weight, overweight, obese) -Genetics To determine if each possible risk factor is related to glucose levels, researchers need to use an appropriate hypothesis test. Use Table 7-50 on page 161 of the textbook to select the correct test from the gray box above. What test would be used to assess whether the different sexes (male and female) have the same proportions of the different glucose levels? What test would be used to assess whether the different glucose levels have the same mean age? What test would be used to assess whether the different categories of BMI…
Have you heard of “pet therapy”? Access to a pet (typically, but not limited to, a dog) has been shown to be associated with beneficial physical responses like lowered blood pressure and reduced anxiety. In a review of the pet therapy literature, Giaquinto and Vlanetini (2009) describe a study that compared two groups of heart patients. Group 1 consisted of patients with high blood pressure and who owned pets. These participants were matched with participants in a control group who also had high blood pressure but did not own pets. Six months later, blood pressure was measured in both groups. Does having a pet reduce blood pressure? what statistical test should be used and why?
1) Soda consumption is very common in the U.S. For the purposes of this question, assume that 30% of the population consumes the equivalent of 3 or more 12 oz. sodas per week (this is the prevalence of the exposure). A large multi-center cohort study was conducted to evaluate the association between soda consumption and risk of diabetes. At baseline, participants were asked about their typical soda consumption, and individuals who reported consuming 3 or more sodas per week were considered exposed. Participants were followed for 10 years, and the following results were obtained: Incident Cases of Diabetes 356 236 Person-Years Contributed 3+ sodas a week 375234 <3 sodas a week 399763 a) Name the appropriate measure of association corresponding to the excess rate of diabetes attributable to soda consumption among subjects who consume 3+ sodas per week. Calculate this measure (shown as a rate, using the correct units), and provide a brief interpretation of your answer b) Calculate the…
Carter et al investigated the effect of age at onset of bipolar disorder on the course of the illness. One of the variables studied was the subjects' family history. The table below shows the frequency of a family history of mood disorders in the two groups of interest: early age at onset (18years or younger) and later age at onset (later than 18 years old). Can we conclude on the basis of these data that subjects 18 or younger differ from subjects older than 18 with respect to family histories ofmood disorders? Ref: J Psychiatric Research 37(2003), 297-303.

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