INSTRUCTIONS:• Please answer the questions using this Word document; please do NOT delete the actual questions!

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HOMEWORK 2MAT 461 – BiostatisticsYour NameDate

Questions (please statistically justify all your answer):

10 points, out of 100 points, are assigned to correct scientific writing:• use full sentences to answer the questions• use correct grammar• use sentences that make sense

[5] 1. What is this article about? In other words, what is the hypothesis tested in this study?

[5] 2. Describe and define the study presented in this paper; please include study type, study length (with start and end dates), sampling method, participants’ information, vitamins used.

[5] 3. What are the end points measured in this study?

[15] 4. Refer to Figure 1 on page 1873:a. Overall, how many people were screened for the study and how many were excluded from the study? Please show your calculations.

b. What are the names and sample sizes of each group, and what is the overall sample size of this study?

c. In the Placebo group, what is the attrition rate at the end of the study in 2011? Please show your calculations.

[60] 8. Refer to Table 1 on page 1874:a. What do you understand by baseline characteristics?

b. Statistically, what do the characteristics in the first column represent, parameters, statistics, or variables?

c. Statistically, what do the values in columns 2 and 3 represent, parameters, statistics, or variables?

d. In the context of this table, please list which characteristics are:

QUANTITATIVE

QUALITATIVE:

e. How many men taking vitamins never smoked?

f. What percentage of men taking vitamins exercise more than once per week?

g. What percentage of men on placebo are older than 70?

h. For men taking vitamins, what does the number 4.26 represent (see bottom of the table)?

i. For men taking vitamins, what do the numbers 2.95 and 5.75 in the interval (2.95-5.75) represent (see bottom of the table)? Please write a sentence to interpret this interval.

j. Refer to the body mass index (BMI) characteristic:j1. Explain what the number 25.9 represents.

j2. Explain what the number 3.4 represents (in the Placebo group).

j3. Based on the men’s mean BMI, please state whether the men in each group are underweight, normal, overweight or obese.

j4. Which group shows the least variation in BMI? Why?

j5. Estimate the BMI range for the majority of men on placebo.

k. For men taking vitamins, what were their mean and standard deviation age and BMI levels? Please show the units for each statistic.

Mean Standard DeviationAge BMI

l. For men taking vitamins, determine which of the two measures, Age or BMI, varies more. Please justify your answer.

m. Based on the data presented in this table, are there any confounders? Please justify your answer.