A study was performed looking at the effect of physical activity on cognitive
Table 8.23 Mean difference from baseline (18-month score minus baseline score) among participants with mild cognitive impairment in the ADAS-Cog score*
*A negative change indicates improvement since high values on the testindicate worse cognitive function
What test can be performed to compare the mean change in the two groups at 18 months?
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Fundamentals of Biostatistics
- A Canadian study measuring depression level in teens (as reported in the Journal of Adolescence, vol. 25, 2002) randomly sampled 112 male teens and 101 female teens, and scored them on a common depression scale (higher score representing more depression). The researchers suspected that the mean depression score for male teens is higher than for female teens, and wanted to check whether data would support this hypothesis. What conclusion can you draw from the output? The data provide sufficient evidence to reject H0 and to conclude that the mean depression score for male teens is larger than that of female teens. The data provide sufficient evidence to conclude that male and female teens do not differ in mean depression score. The data do not provide sufficient evidence to conclude that the mean depression score of male teens is larger than that of female teens. The data do not provide sufficient evidence to reject H0, so we accept it, and conclude that male and female teens do…arrow_forwardRogers, Farlow, and colleagues (1998) conducted an experiment to investigate whether donepezil improved cognitive function in patients with mild to moderate Alzheimer’s disease (AD). A total of 1,775 patients were randomly assigned to treatment with either donepezil or a placebo (a look-alike pill with no pharmacological effect). Cognitive function, as measured by the Alzheimer’s Disease Assessment Scale (ADAS-cog), was significantly improved in patients taking donepezil compared with the placebo group at weeks 12, 18, and 24. [Source: Rogers, S. L., Farlow, M. R., Doody, R. S., et al. (1998). A 24-week, double-blind, placebo controlled trial of donepezil in patients with Alzheimer’s disease. Neurology, 50, 136–145.] In this experiment, the independent variable is , and the dependent variable is . The individuals who are in the control condition are typically referred to as the control group. Here, the control group consists of . is a construct that is being tested in this…arrow_forwardA case–control study of patients on antihypertensive drugs related an increased risk of myocardial infarction (MI) for patients using calcium channel blockers (Psaty, et al.,1995). In this study, cases were antihypertensive drug patients who had suffered a first fatal or nonfatal MI through 1993, and controls were antihypertensive patients, matched by demographic factors, who had not suffered a MI. Among the comparisons reported were patients receiving calcium channel (CC) blockers (with and without diuretics) and patients receiving β–blockers (with and without diuretics). Results of numbers of patient by drug/MI status combination are given in Table 1. Compute the odds ratio of suffering MI (CC blockers relative to β–blockers), and the corresponding 95% CI. Does it appear that calcium channel blockers are associated with higher odds (and thus probability) of suffering MI than β –blockers? Table 1: Observed cell counts for antihypertensive drug/MI data Occurrence of…arrow_forward
- Landolt et al. (A-26) examined rates of posttraumatic stress disorder (PTSD) in mothers and fathers. Parents were interviewed 5 to 6 weeks after an accident or a new diagnosis of cancer or diabetes mellitus type I for their child. Twenty-eight of the 175 fathers interviewed and 43 of the 180 mothers interviewed met the criteria for current PTSD. Is there sufficient evidence for us to conclude that fathers are less likely to develop PTSD than mothers when a child is traumatized by an accident, cancer diagnosis, or diabetes diagnosis? Let alpha = 0.05arrow_forwardDowns and Abwender (2002) evaluated soccer players and swimmers to determine whether the routine blows to the head experienced by soccer players produced long term neurological deficits. In the study, neurological tests were administered to mature soccer players and swimmers and the results indicated significant differences. In a similar study, a researcher obtained the following data. Swimmers Soccer Players 10 7 8 4 7 9 9 3 13 7 7 6 12 a)Are the neurological test scores significantly lower for the soccer player than for the swimmers in the control groups? Use a one-tailed test with = .05. b)Compute the value of r² (percentage of variance accounted for) these data.arrow_forwardDoes posting calorie content for menu items affectpeople’s choices in fast-food restaurants? According to results obtained by Elbel, Gyamfi, and Kersh(2011), the answer is no. The researchers monitoredthe calorie content of food purchases for children andadolescents in four large fast-food chains before andafter mandatory labeling began in New York City. Although most of the adolescents reported noticing thecalorie labels, apparently the labels had no effect ontheir choices. Data similar to the results obtained showan average of M = 786 calories per meal with s =85 for n =100 children and adolescents before thelabeling, compared to an average of M = 772 calorieswith s = 91 for a similar sample of n = 100 after themandatory posting.a. Use a two-tailed test with a = .05 to determinewhether the mean number of calories after theposting is significantly different than before caloriecontent was posted.b. Calculate r2to measure effect size for the mean difference.arrow_forward
- A RCT was published in JAMA in July 2016 to determine whether palliative care-led family meetings reduced the presence of anxiety and depression symptoms among family caregivers of patients with chronic critical illness, as compared to routine care. Researchers reported a difference in anxiety and depression symptoms (measured by the Hospital Anxiety and Depression Scale [HADS] symptom score) between the two arms of 0.8 over a 3-month period, with the P-value being 0.34. In the RCT described above, is the result statistically significant or not? Alpha was set at 0.05. Explain your answer.arrow_forwardIn a 2002 study conducted on 3000 Italian 15-year-old females, girls were asked how often they consume kaleeach week. Four years later, these answers were linked to the girls’ intelligence test scores as 19-year-olds. Thestudy found that girls who consume kale at least once a week scored higher on the intelligence test.Is this an experiment or an observational study? Explain. What is the explanatory variable? What is the response variable?arrow_forwardA 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.arrow_forward
- Glencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw Hill