You must turn in a knitted file to Gradescope from a markdown file in order to receive credit. More details will be provided at the end of this document, and we will also review the process during class. Be sure to “associate” questions appropriately on Gradescope. As a reminder, late work is not accepted outside of the 24-hour grace period for homework assignments.

The R Markdown template for this assignment may be found by running the following code in your Console.

download.file("https://www2.stat.duke.edu/courses/Fall20/sta102/hw/hw-01-template.Rmd", destfile="hw-01.Rmd")

Ahmed et al. (JAMA Neurology, 2016) conducted a study examining disturbances in eating behaviors among patients with dementia. Patients without dementia, with Alzheimer disease (AD), with semantic dementia, and with behavioral-variant frontal temporal dementia (bvFTD) were offered a breakfast buffet and left alone for 30 minutes to eat. After completion, the total caloric intake of each patient was measured. Boxplots summarizing the distributions of calories consumed across the patient types are displayed below.

  1. 5 points Was this an observational study or an experimental study? Explain.
  2. 7 points Describe what it means for this specific study to be reproducible and replicable.
  3. 15 points What type of data are the following variables in the study? Be specific, e.g., “categorical ordinal” or “numeric discrete,” etc.
  1. 5 points Do you expect the distribution of caloric intake among bvFTD patients to be left-skewed, right-skewed, or symmetric? Why?
  2. 7 points Describe an appropriate visualization that summarizes the % of calories from sugar at the breakfast buffet to the Frontal Rating Scale of the study participants.
  3. 8 points Describe an appropriate visualization that summarizes the total caloric intake at the breakfast buffet, disease duration in years, and type of dementia among these study participants.
  4. 8 points The authors state that they uncovered “elevated total caloric intake…in patients with bvFTD, supporting its diagnostic value for this disease….” Is this is a reasonable statement to make from the data visualization? Explain why or why not.
  5. 5 points Suppose the authors wanted to “tell a story” with the title to their visualization. Suggest a more effective title than the one presented.

Zhu et al. (The Lancet, 2020) conducted the first randomized trial of a recombinant adenovirus COVID-19 vaccine in healthy adults, with the aim of determining an appropriate dose for a larger efficacy study. They had three treatment arms: placebo, low dose (5 \(\times\) 10\(^{10}\) virus particles), and high dose (1 \(\times\) 10\(^{11}\) virus particles). The following table depicts the baseline characteristics of their study population:

Calculate the following probabilities. It’s ok to express answers as unsimplified fractions). If the probabilities cannot be determined, please state so and what additional information is needed to calculate the quantity of interest.

What is the probability that a randomly selected patient in the trial …

  1. 5 points …was assigned to placebo?
  2. 5 points …was assigned to placebo or was male?
  3. 5 points …was assigned to placebo and was male?
  4. 5 points …was not assigned to high dose vaccine and had no underlying diseases?
  5. 5 points …was female or had underlying diseases?
  6. 5 points …was female or was not assigned to either vaccine dose?
  7. 5 points …was aged 18 - 44, given that they were assigned to high dose vaccine?
  8. 5 points …was not assigned placebo, given that they were aged 45-54?

Submission: You can knit the template into an .html file that can be opened by any web browser by clicking on the Knit in the bar above the scriping area, as demonstrated in class. To export this document as a .pdf, open the .html file in your web browser of choice and then print to or save as a .pdf document. (There is a way to directly knit to a .pdf file, but it’s quite a bit more involved…).

Turn in this .pdf document into Gradescope in the appropriate assignment area. You will be asked to “associate” pages with questions - click on the appropriate page that each question is on. If you do not associate pages properly, the TAs will not be able to see your submission for grading purposes!