A case control study was carried out to investigate the relationshipbetween Vitamin D levels and individuals who contracted COVID-19needing hospitalisation. Table 2 shows the results of the study.Table 2Vitamin D levelsOptimal >25ng/mLMild deficiency 10ng/mL-24ng/mLSevere deficiency >10ng/mLTotalHospitalised with COVID-19YesNo339825156V44148120.90 0.95 0.975 0.99 0.995 0.9991 2.71 3.84 5.02 6.63 7.88 10.837.38 9.21 10.609.35 11.34 12.842 4.61 5.993 6.25 7.814 7.78 9.4913.8216.2711.14 13.28 14.86 18.47204Total(b) How many degrees of freedom are there?Table 3: Selected Quantiles for chi-squared distributions(a) Calculate the chi-squared test statistic for the association betweenVitamin D levels and needing hospitalisation for individuals whocontract COVID19.7724637360

(a) Null hypothesis: Alternative hypothesis:

Answered: A case control study was carried out to…

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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Researchers conducted a study investigating the number of viralinfections people contracted as a function of their stress over a 6-month period. Use the provided steps to conduct a one-factor between-subjects ANOVA that test whether there are any differences in number of infections across the four conditions.a. State the hypotheses. b. Determine the critical value for an alpha level of 0.05.
A company manufactures an electrical cooling fan. When the fans are performing properly, samples of 200 fans average 12.5 watts with an average range of 1.2 watts. A 3σ control chart program is being used to monitor the performance of the fans, and these data from the 10 most recent samples were collected: Sample Number Sample Mean Sample Range 1 12.5 1.1 2 12.45 1.2 3 12.55 0.9 4 12.50 0.8 5 12.45 0.9 6 12.60 1.0 7 12.48 1.4 8 12.46 1.1 9 12.56 0.9 10 12.48 0.8 Compute the 3σ control limits and center line for an ⁻x chart. Compute the 3σ control limits and center line for an R chart. Plot the sample data on the ⁻x and R charts and decide if the performance of the fan is in control.
The effectiveness of surgery for weight loss reported here found that "The surgery was associated with significantly greater weight loss [than the control group who dieted] through 2 years (61.3 versus 11.2 pounds, P<0.001)." What test could have been used and how would it have been computed?
Devise a hypotheses for the research question: Is there singificant correlation between students height and typical amount of sleep a student gets per night? Identify the appropriate statistical test using alpha = 0.05. Perform the statistical test. Use descriptive statistics to describe the variables both numerically and graphically. Height (whole inches) Sleep (minutes) 60 360 62 400 66 420 68 440 68 540 70 480 72 320 75 440 66 360 63 420 69 420 75 390 69 360 67 480 69 360 73 360 69 480 70 420 68 360 63 480 69 270 68 360 71 420 71 360 62 420
Productivity is the key driver of wages and one of the most importantdeterminants of living standards. The British Chambers of Commercecommissioned research into understanding whether labour productivity in theautomotive manufacturing sector in England and Ireland were the same ordifferent. The researchers collected data on a random sample of 8 firms inEngland and 4 in Ireland and recorded productivity in units of value added (£)per hour. It is assumed that firm-level productivity has a normal distribution.The following data were collected:Ireland 47 56 43 68England 39 50 39 45 50 43 35 43(i) Set up appropriate null and alternative hypotheses and conduct a test ofthe hypotheses of equal mean productivity in Ireland and England at 5 percent significance level under the assumption of unknown but equalpopulation variances. Provide as much detail as possible on yourprocedures. Clearly show all your steps in testing and state your decision.Discuss the economic implications of your findings.…
widely used as dielectrics and coolants in electrical systems in the past. They were found to be a major environmental contaminant in the 1960s. In a study, the mean PCB content at each of thirteen sites was reported for the years 1982 and 1996 (from “The ratio of DDE to PCB concentrations in Great Lakes herring gull eggs and its use in interpreting contaminants data”, Journal of Great Lakes Research 24 (1): 12-31, 1998). The data are below.Site:12345678910111213198261.4864.4745.5059.7058.8175.9671.5738.0630.5139.7029.7866.8963.93199613.9918.2611.2810.0221.0017.3628.207.3012.809.4112.6316.8322.74(a) Which test would be more appropriate in this case: a t-test for the difference between two population means, or a paired t-test? Why?(b) Do the data provide sufficient evidence to support the claim that the mean PCB level has decreased in the region? Be sure to check all assumptions, write the null and alternative hypotheses, calculate the appropriate test statistic, calculate the p-value,…
A survey of the population of 51 students in Psych 311 asks how many credits students are taking and obtains the following normally-distributed results: ∑ X= 686 and ∑X2= 9832.92. Using this information, answer the following three questions. What is the percentile rank of a student who is enrolled in 15 credits? (Hint: This is the same thing as asking “what percentage of students is enrolled in 15 credits or less?”) MUST SHOW WORK FOR THIS PROBLEM What percentage of students are enrolled in between 12 and 18 credits? (MUST SHOW WORK FOR THIS PROBLEM) What is the 25th percentile? (Hint: This is the same as asking what score separates the bottom 25% of the distribution from the top 75%.) MUST SHOW WORK FOR THIS PROBLEM
A clinical trial is run to assess the effects of different forms of regular exercise on HDL levels in persons between the ages of 19 and 29. Participants in the study are randomly assigned to one of three exercise groups—weight training, aerobic exercise, or stretching/yoga—and instructed to follow the program for 8 weeks. Their HDL levels are measured after 9 weeks and are summarized below. Exercise Group N Mean Std Dev Weight Training 20 49.7 10.2 Aerobic Exercise 20 43.1 11.1 Stretching/Yoga 20 57.0 12.5 Complete the following ANOVA table. Source of Error Sums of Squares df Mean Squares F Between Within 6157.32 Total 1.Write the hypotheses to be tested. 2. Write the decision rule. Please find the F for the closest df 3. What is the conclusion?
A certain polymer is used for evacuation systems for aircraft. It is important that the polymer be resistant tothe aging process. Fifty specimens of the polymer were used in an experiment. Twenty‐five were assignedrandomly to be exposed to an accelerated batch aging process that involved exposure to high temperatures for10 days. Question Which Treatment results in the higher mean tensile strength? (Circle One) Aging or No AgingWhich Treatment has the higher variability? (Circle One) Aging or No Aging
10.20 In a random sample of recent high school graduates, two characteristics were recorded (the average score and the number of correct answers for the SAT test). This information was classified as shown in Table 10.8. Is there a dependence between the number of correct answers on the SAT test and the average rankings statistically discernible at a level α = 0.01?
A researcher was interested in comparing the resting pulse rate of people who exercise regularly and people who do not exercise regularly. Independent random samples of 16 people aged 30-40 who do not exercise regularly (sample 1) and 12 people aged 30-40 who do exercise regularly (sample 2) were selected and the resting pulse rate of each person was measured. The summary statistics are as follows: Pulse Rate data Group 1 (no exercise) Group 2 (exercise) average 72.7 69.7 standard deviation 10.9 8.2 sample size 16 12 Test the claim that the mean resting pulse rate of people who do not exercise regularly is greater than the mean resting pulse rate of people who exercise regularly, use 0.01 as the significance level. Round you answer to 3 decimal places. Group of answer choices p-value=0.207, evidence not support claim p-value=0.267, evidence support claim p-value=0.414, evidence not support claim p-value=0.793, evidence not support claim p-value=0.207, evidence…
Dr. Maddan's eye drops are supposed to cause significant reduction is eye redness. The following table shows the results of a recent study where a random sample of individuals took part in a placebo controlled study. No Reduction in Redness Reduction in Redness Total Eye Drops 120 220 340 No Eye Drops Total 120 140 260 240 360 600 With 5% level of significance, determine if eye redness reduction is dependent upon taking the eye drops. Provide, a. the Chi-square statistic. b. the critical value or the p-value. c. Your decision on whether or not to reject Ho.

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