What are the strengths and the weaknesses of experimental designs?
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What are the strengths and the weaknesses of experimental designs?
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- A student was interested in the impact of nutrition and exercise on mental health. She recruited a sample of 80 individuals. She divided the participants into 4 groups. One group was a control group. There was no treatment for this group. The second group was the diet group. These participants followed a strict diet that was designed by a dietitian. The nutrients in the diet were optimized for each individual. The third group was an exercise group. These participants worked with a personal trainer on an individualized exercise plan. The fourth group was the exercise and diet group. This group had both the dietitian and personal trainer intervention. After 3 weeks of treatment (or control), She measured their mental health with the Warwick-Edinburgh Mental Well-being Scale (WEMWBS). Some of the information is included in the ANOVA table below but I spilled a coffee on the output and the student already deleted the raw data...oh, no!! Given the ANOVA table below, what is the F-statistic?…Based on Angel et al. (2003). A fertilizer companyis trying to determine the cheapest fertilizer mix thatprovides desired amounts of nutrients. The mix ismade by combining the following fertilizers: SSA,SPO, GUR, TSP, KCI, FERT, and SPF. The mix cannot contain both GUR and TSP. The percentage ofpotassium (K), sulfur (S), calcium (Ca), sodium (Na)and phosphorus (P) in each fertilizer is listed in the fileP06_88.xlsx. For example, a pound of SSA is 16% Kand 26% Na. The mix must contain at least 600 poundsof K, 550 pounds of S, 750 pounds of Ca, 900 poundsof Na, and 750 pounds of P. The mix cannot containboth GUR and TSP, because if both are present in themix, the affect of other fertilizers is nullified. The costper pound (in cents) of each fertilizer is listed in thesame file. Develop a linear integer model to find theminimum-cost fertilizer mixture that meets the statedchemical requirements.A national study found that treating people appropriately for high blood pressure reduced their overall mortality by 20%. Treating people adequately for hypertension has been diffcult because it is estimated that 50% of hypertensives do not know they have high blood pressure, 50% of those who do know are inadequately treated by their physicians, and 50% who are appropriately treated fail to follow this treatment by taking the right number of pills. Answer the following questions ( please answer all the parts 1,2 and 3): 1) What is the probability that among 10 true hypertensives at least 50% are being treated appropriately and are complying with this treatment?2) What is the probability that at least 7 of the 10 hypertensives know they have high blood pressure? 3) If the preceding 50% rates were each reduced to 40% by a massive education program, then what effect would this change have on the overall mortality rate among true hypertensives; that is, would the mortality rate decrease…
- What are the assumptions underlying the predator-prey model discussedin this section?A quality control engineer studied the relationship between years of experience as a system control engineer and the capacity of the engineer to complete within a given time a complex control design including the debugging of all computer programs and control devices. A group of 25 engineers having widely differing amounts of experience (measured in months of experience) was given the same control design project. The results of the study are given in the following table with y 5 1 if the project was successfully completed in the allocated time and y 5 0 if the project was not successfully completed. a. Determine whether experience is associated with the probability of completing the task. b. Compute the probability of successfully completing the task for an engineer havinganswer part 2 frq styed please and show work 1. Because of the constantly evolving political climate around the United States, Gallup (who regularly conducts polls in the U.S.) conducted a poll just after the inauguration asking U.S. adults if they approve of the initiatives President Biden had implemented in his first few days in office. Another Gallup poll was conducted now that President Biden has been in office for a month asking U.S. adults if they approve of the initiatives President Biden had implemented after his first month in office. According to the first Gallup poll of 1500 randomly selected U.S. adults, 64% approved of the initiatives President Biden had implemented in his first few days in office. And according to the second Gallop poll of 1700 U.S. adults, 54% approved of the initiatives President Biden had implemented after his first month in office. Construct and interpret a 95% confidence interval for the change (difference) in the true proportion of U.S. adults…
- Maple syrup is a non-negligible nutritional source of manganese. It is made from the sap of two species of maple: the sugar maple and the black maple. To see if there is a significant difference between the manganese content of these two species of maple, we measured the manganese content (in mg per 100g syrup) for a sample of sugar maples and a sample of black maples. The data is summarized by the Minitab output below: Two-sample T for Sugar Maple Black Maple group N Mean St Dev SE Mean Sugar Maple 20 Black Maple 12 3.55 0.29 Find: (i) a point estimate for ₁-2, where ₁ and 2 are the average manganese contents of the sugar maple, respectively the black maple; (ii) the standard error of X₁ - X₂. A) (i) -0.07; (ii) 0.101 C) (i) -0.26; (ii) 0.097 E) (i) -0.07; (ii) 0.035 3.29 0.22 0.049 0.084 B) (i) -0.26; (ii) 0.188 D) (i) -0.26; (ii) 0.101What is a dummy variable trap and how is it related to multicollinearity of regressors? What is the solution for this form of multicollinearity?You oversee assessing different training methods for effectiveness. You have data on 4 methods: Method 1 (?1 = 87, ?1= 12), Method 2 (?2= 92, ?2 = 14), Method 3 (?3= 88, ?3 = 15), and Method 4 (?4=75, ?4 = 11). Test for differences among these means, assuming ??B=64.81 and ??T=399.45.
- One of the main issues that censuses are not considered as a feasible option for studies beside being logistically demanding is: Select one: a. Populations contains too many variables and cannot be analyzed. b. Censuses are not accurate because we cannot use statistics with it. c. None of the mentioned reasons is a valid reason. d. Samples are easier to work with than census that is what makes use samples. e. Populations are dynamic and very rarely stand still.Overhead Door (OD) Corporation’s founder, C. G. Johnson, invented the upward-lifting garage door in 1921 and the electric garage door opener in 1926. Since then OD has been a leading supplier of commercial, industrial, and residential garage doors sold through a nationwide network of more than 450 authorized distributors. They have built a solid reputation as a premier door supplier, commanding 15 % share of the market. Suppose that customers assess door quality first in terms of the ease of operation, followed by its durability. The quality improvement team (QIT) might then assign an engineering team to determine the factors that contribute to these two main problems. Smooth operation of a garage door is a critical quality characteristic that affects both problems: If a door is too heavy, it’s difficult and unsafe to balance and operate; if it’s too light, it tends to buckle and break down frequently or may not close properly. Suppose the design engineers determine that a standard…1. In an effort to determine whether a new type of fertilizer is more effective than the type currently in use, researchers took twelve 2-acre plots of land scattered throughout the county. Each plot was divided into two equal-sized subplots, one of which was treated with the current fertilizer and the other of which was treated with the new fertilizer. Wheat was planted, and the crop yields measured. These data are in the table below New Fertilizer current Fertilizer 39 36 75 68 44 77 87 85 96 90 85 84 65 60 a. Can we conclude at the 5% significance level that the new fertilizer is more effective than the current one?, That is to say , test the hypothesis Но: и — и, — 0 versus Ha: д — и, >0 for a %3D.05. b. Estimate with 95% confidence the difference in mean crop yields between the two fertilizers.