MPH5041 Introduction to Biostatistics - Assessment 2

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Data Description (CVD-Data): Consider a study where twelve baseline variables (e.g., age, gender, weight, BMI, etc.) among others were collected from each of the 1429 participants. Out of the 1429 participants, 952 had a history of being treated with Drug-X on a regular basis. The objective of the study was to investigate whether Drug-X was protective for various risk factors of cerebrovascular vascular disease (CVD). The participants were then followed for 5 years and their mortality status was recorded. The short and long names of the variables are given in Table 1. Note: Baseline Variable is collected at the beginning of a study.

Table 1: Variable description for the study

Variable Description Statistical Code (if any)
GENDER Gender 0 for female and 1 for male
BMI Body mass index 0 for <25; 1 for 25 to <30; 2 for

30 to <35 and 3 for 35 and above

SBP Systolic blood


DBP Diastolic blood


CHL Cholesterol level N/A
SMOKE Smoking status 0 for never smoked and 1 for


Drug-X Drug ‘X’ treated 0 for no and 1 for yes
PAD Peripheral arterial


0 for no and 1 for yes
STROKE Stroke 0 for no and 1 for yes
DEATH Follow-up mortality


0 for no and 1 for yes

Questions 1-4 are related to the CVD-Data and Question 5 is related to the diastolic blood pressure (DBP) Data.

Important reminder:

  • Read the questions carefully and please adhere to what the question is asking Also read the Assessment 2 Information Book (e-book).
  • Qs 2-4 - Please report your findings for all variables under one common heading in each

Question 1 [5 marks]: Consider that an investigator aims to assess whether ‘Drug-X’ was protective for ‘mortality’ in the study sample. Evaluate the investigator’s aim by presenting the related data on an appropriate graph (Hint: no additional summary statistics or significance test required for answering this question).

Question 2 [35 marks]: Using appropriate statistical method(s) investigate whether patients who had a history of being treated with Drug-X on a regular basis have significantly different systolic blood pressure (SBP), diastolic blood pressure (DBP) and cholesterol level (CHL) compared to patients without Drug-X treated.

Please fill up the following table from the above analysis results.

Variable Summary statistics p-value 95% CI (where appropriate)
Yes Drug-X No Drug-X
Systolic      blood

pressure (SBP)

Diastolic     blood pressure (DBP)        
Cholesterol level (CHL)        

Question 3 [20 marks]: Using appropriate statistical methods evaluate the significance of difference of CHL and SBP between the BMI categories.

Question 4 [20 marks]: Using appropriate statistical methods compare patients’ SBP and DBP by STROKE status.  Hint: Statistical significance test required.

Question 5 [15 marks]: In a clinical trial, 35 subjects were treated with a new drug to show the efficacy of the drug in reducing diastolic blood pressure (DBP). Their blood pressure was observed before the treatment and after 10 weeks of the treatment (see the DBP-data on the Moodle site). Using appropriate statistical method(s) evaluate whether the drug is significantly effective.

Question 6 [5 marks]: State the learning outcomes of Modules 4-7 and describe how this assessment is aligned with these learning outcomes (maximum of 150 words, this will be excluded from the total word count of this assessment).

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