Introductory Biostatistics Courses

401077 Introduction to Biostatistics, Autumn 2020
Assignment 1 (Due Sunday March 29, 2020)
Please answer all 7 questions. Record your answers in the template document provided and submit via
Turnitin before 11:59pm on the due date. The marks allocated to each question are shown in the
assignment. A total of 30 marks are available and this assignment is worth 30% of your overall grade.
Some of the questions require you to analyse the unique assignment data set which I have created for
you. This is labelled ‘dataforxxxxxxxx.RData’ where xxxxxxxx represents your Student ID number.
The description of this data set is provided in the file ‘Description of your data set.docx’. You can
find your data set and its description into the Assessment 1 folder in vUWS.
Note: Each student will get different answers as the data sets differ.
Question 1 (2 marks)
Consider the sample from the Framingham Study assigned to you for your assignment.
a) Explain why heart rate (heartrte) is a quantitative variable. (1 mark)
Quantitative variables are variables with numerical values where arithmetic operations such
as addition, multiplication, subtraction and division can be carried on. The heart rate is
numeric and these operation can suffice. For instance it is possible to compute the mean heart
rate for the data hence it is quantitative.
b) Explain why your student number (yourID) is not a variable. (1 mark)
The student number is only important in tracing the questionnaires and where the data
originated from. It cannot be useful in making any generalization on the data hence it is not a
variable.
Question 2 (4 marks)
a) Using the sample from the Framingham Study assigned to you and R Commander, graph the
distribution of serum total cholesterol (totchol). Provide an appropriate title and descriptive
axis labels. (1 mark)
Histogram can be used to show the distribution serum total cholesterol (totchol) as follows;

b) Using appropriate statistics from R Commander, write one or two sentences describing the
distribution of serum total cholesterol (totchol). (Hint: consider measures of centre, spread
and shape. R commander output alone is insufficient – write the answer in your own words.)
(3 marks)
Min. 1st Qu. Median Mean 3rd Qu. Max. NA's
133 205 232 234 256 600 4
As seen in the histogram above,the total cholesterol distribution is positively skewed.More
data if found on the right hand side.The value of mean >median hence shoving that the data is right-
skewed.The mean cholesterol for all the subjects was 234 mg/dL with a median of 232 mg/dL.The
standard deviation was 43.50 mg/dL.The lowest recorded cholesterol amount was 133 mg/dL with
600 mg/dL being the highest amount of cholesterol recorded.
Question 3 (3 marks)
Using the sample from the Framingham Study assigned to you and R Commander, graph the
frequency distribution of ‘Attained education’ (educ_f). Provide an appropriate title and descriptive
axis labels. Write a sentence or two summarising the main characteristics of this distribution as shown
by the graph. (3 marks)
The Attained education was "0-11 years", "High school diploma", "Some college", “College degree"
with frequency distribution of 132, 86, 46 and 39 respectively. These were substituted with letters to
fit in the bar graph such as 0-11 years-A, High school diploma-B, Some college-C, and College
degree-D
The results revealed a skewed distribution where the distribution of subjects decreased with increase
with education level. The study subjects who had attained less education were more compared to them
that had attained higher education.

Question 4 (4 marks)
Using the sample from the Framingham Study assigned to you and R Commander, graph respondents’
‘serum total cholesterol’ (totchol) against ‘Attained education’ (educ_f). ). Provide an appropriate title
and descriptive axis labels. Using the graph and associated statistics, write a sentence or two
describing the relationship between these two variables. (4 marks)