Scientists claim that there is a possible relationship between the severity of Covid-19 and a low level of blood vitamin D. The normal level for vitamin D is around 30ng/ml. For this reason, the vitamin D blood level has been measured for 2 countries, A and B, and recorded in a Microsoft Excel file (Vitamin D.xlsx). Enter this Excel file into the statistical package of your choice and answer all questions: (Please add the code and output to your answers.) a) Find the number of observations, mean, standard deviation of vitamin D level for the variables Country, Gender, and Sun_Exposure using the statistical package of your choice: b) Write down the statistical hypotheses for three separate analyses comparing the means of the groups in the following variables: (1) Country, (2) Gender, and (3) Sun_Exposure. Estimate the treatment effects for each of these three factors. Note: For the next questions, use a statistical software to randomly sample 30 observations for each Country, and save this subset of observations in a new dataset called "Question_1_Country". In SPSS: Data > Select Cases > Random sample of cases (you can save the random observations as a .sav or an excel file, if using SPSS). In R: you can use the following code to perform this random sampling. Learn this procedure as you may need to use it for other sections. Note: every time you run the following code, you will get a different dataset. Therefore, you will get different outputs (because of the random nature of random sampling). ### 30 Random observations for Country A ### Country A <- subset (Vitamin D, subset= Country="A") C.A - Country A[sample (nrow(Country_A), 30),] ### 30 Random observations for Country B ##* Country B <- subset (Vitamin D, subset= Country="B") C.B < Country B[sample (nrow(Country B),30),]
Scientists claim that there is a possible relationship between the severity of Covid-19 and a low level of blood vitamin D. The normal level for vitamin D is around 30ng/ml. For this reason, the vitamin D blood level has been measured for 2 countries, A and B, and recorded in a Microsoft Excel file (Vitamin D.xlsx). Enter this Excel file into the statistical package of your choice and answer all questions: (Please add the code and output to your answers.) a) Find the number of observations, mean, standard deviation of vitamin D level for the variables Country, Gender, and Sun_Exposure using the statistical package of your choice: b) Write down the statistical hypotheses for three separate analyses comparing the means of the groups in the following variables: (1) Country, (2) Gender, and (3) Sun_Exposure. Estimate the treatment effects for each of these three factors. Note: For the next questions, use a statistical software to randomly sample 30 observations for each Country, and save this subset of observations in a new dataset called "Question_1_Country". In SPSS: Data > Select Cases > Random sample of cases (you can save the random observations as a .sav or an excel file, if using SPSS). In R: you can use the following code to perform this random sampling. Learn this procedure as you may need to use it for other sections. Note: every time you run the following code, you will get a different dataset. Therefore, you will get different outputs (because of the random nature of random sampling). ### 30 Random observations for Country A ### Country A <- subset (Vitamin D, subset= Country="A") C.A - Country A[sample (nrow(Country_A), 30),] ### 30 Random observations for Country B ##* Country B <- subset (Vitamin D, subset= Country="B") C.B < Country B[sample (nrow(Country B),30),]
MATLAB: An Introduction with Applications
6th Edition
ISBN:9781119256830
Author:Amos Gilat
Publisher:Amos Gilat
Chapter1: Starting With Matlab
Section: Chapter Questions
Problem 1P
Related questions
Question
![Scientists claim that there is a possible relationship between the severity of Covid-19 and a
low level of blood vitamin D. The normal level for vitamin D is around 30ng/ml. For this reason,
the vitamin D blood level has been measured for 2 countries, A and B, and recorded in a
Microsoft Excel file (Vitamin_D.xlsx). Enter this Excel file into the statistical package of your
choice and answer all questions: (Please add the code and output to your answers.)
a) Find the number of observations, mean, standard deviation of vitamin D level for
the variables Country, Gender, and Sun_Exposure using the statistical package of your
choice:
b) Write down the statistical hypotheses for three separate analyses comparing
the means of the groups in the following variables: (1) Country,
(2) Gender, and (3) Sun_Exposure.
Estimate the treatment effects for each of these three factors.
Note: For the next questions, use a statistical software to randomly sample 30
observations for each Country, and save this subset of observations in a new dataset
called "Question_1_Country".
In SPSS: Data > Select Cases > Random sample of cases (you can save the random
observations as a .sav or an excel file, if using SPSS).
In R: you can use the following code to perform this random sampling. Learn this
procedure as you may need to use it for other sections.
Note: every time you run the following code, you will get a different dataset.
Therefore, you will get different outputs (because of the random nature of random
sampling).
### 30 Random observations for Country A ##*
Country A <- subset (Vitamin D, subset= Country="A")
C.A - Country A[sample(nrow(Country A), 30),]
-"A")
### 30 Random observations for Country B ###
Country B <- subset (vitamin D, subset=Country="B")
C.B <- Country_B[sample(nrow(Country_B), 30),]
### Combining them in a new dataset ###
Question 1 Country <- rbind (C.A, C.B)
View(Question_1_Country)](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F17176ae9-b253-442d-89f9-517b049b4c59%2Fbd8494e4-d7f7-40ee-aa4f-5d97b2cb3bc1%2F0xnw3yr_processed.png&w=3840&q=75)
Transcribed Image Text:Scientists claim that there is a possible relationship between the severity of Covid-19 and a
low level of blood vitamin D. The normal level for vitamin D is around 30ng/ml. For this reason,
the vitamin D blood level has been measured for 2 countries, A and B, and recorded in a
Microsoft Excel file (Vitamin_D.xlsx). Enter this Excel file into the statistical package of your
choice and answer all questions: (Please add the code and output to your answers.)
a) Find the number of observations, mean, standard deviation of vitamin D level for
the variables Country, Gender, and Sun_Exposure using the statistical package of your
choice:
b) Write down the statistical hypotheses for three separate analyses comparing
the means of the groups in the following variables: (1) Country,
(2) Gender, and (3) Sun_Exposure.
Estimate the treatment effects for each of these three factors.
Note: For the next questions, use a statistical software to randomly sample 30
observations for each Country, and save this subset of observations in a new dataset
called "Question_1_Country".
In SPSS: Data > Select Cases > Random sample of cases (you can save the random
observations as a .sav or an excel file, if using SPSS).
In R: you can use the following code to perform this random sampling. Learn this
procedure as you may need to use it for other sections.
Note: every time you run the following code, you will get a different dataset.
Therefore, you will get different outputs (because of the random nature of random
sampling).
### 30 Random observations for Country A ##*
Country A <- subset (Vitamin D, subset= Country="A")
C.A - Country A[sample(nrow(Country A), 30),]
-"A")
### 30 Random observations for Country B ###
Country B <- subset (vitamin D, subset=Country="B")
C.B <- Country_B[sample(nrow(Country_B), 30),]
### Combining them in a new dataset ###
Question 1 Country <- rbind (C.A, C.B)
View(Question_1_Country)
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Transcribed Image Text:c) Read the above code carefully and explain what each line is doing
d) To investigate the difference in vitamin D level between countries, write down the
general assumptions of the appropriate statistical test, and check them using graphs
and/or outputs from your statistical package of choice. Note: use the
"Question_1_Country" dataset for this question.
For normality, minimum two graphs
For testing the homogeneity of variances, use Levene's test.
Note: If using R, for Levene's test, install the R package "car".
Does the response variable need any transformation? Why?
e) Compare vitamin D levels for country A and country B at a significance level of 5% using a
t-test, one-way ANOVA, and regression. Compare the results of all three techniques.
For one-way ANOVA use t-test (LSD.test). Plot t-test and regression.
Note: use the "Question_1_Country" dataset for this question.
If you are using R, for the LSD.test function, install the package "agricolae".
Solution
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