Assignment Questions 
Question 1  Determine whether the following scenarios corresponds to an observational study OR experimental study.
If the scenario is an observational study, which one of the observational studies given in the lecture was used and explain why.
If the scenario is an experimental study, which one of the experimental designs given in the lecture was used and explain why.
(a) All patients who received a hip replacement operation at a large hospital during 2000 to 2010 will be followed for 10 years after their operation to determine the success (or failure) of the procedure.
(b) A group of 100 students was randomly selected and randomly divided into two groups. One group of 50 students were assigned to receive a 1000 mg dose of vitamin C and the remaining group of 50 received a placebo, to determine whether vitamin C helps to prevent colds.
(c) A group of office workers and a group of trades people who visited a medical centre were asked to come in for a physical examination every year to monitor and compare their health status.
Question 2  A researcher is assessing how well patients respond to two different dosing regimens of a new drug approved to treat diabetic neuropathy. Two different dosing regimens are administered, and side effects are monitored. Results are shown below in Table 1.
Table 1:
Side Effect Reported

Low Dosage

High Dosage

Nausea

8

21

Headache

3

5

Weight gain

1

0

Weight Loss

0

6

Lethargy

3

11

Skin Rash

13

13

From the above scenario and table, answer the following questions.
(a) What is the independent (explanatory) variable?
(b) What are the dependent (response) variables?
(c) In this study, the researcher measures the side effects as present or not present. What type of variable is this measure?
(d) If instead, the researcher decides to measure weight gain in kilograms, what type of variable would this be?
(e) If instead, the researcher decides to measure nausea as present, limiting or debilitating, what type of variable would this be?
(f) If the researcher measured nausea as the number of hours of nausea experienced in a day, what type of variable would this be?
Question 3  The data given in the data set "Assignment 1.xlsx", gives the observations of a random sample of 89 female students. The data measured the heights (in inches) and fully stretched hand spans (in centimetres) of the female college students.
The Excel data set: Assignment 1.xlsx has the values of all variables.
Using Excel (or hand calculations) answer the following questions:
(a) Using Excel, create the appropriate graph that would display the relationship between height and hand span.
(b) Using Excel, create the appropriate graph that would display the heights of the college students.
(c) Describe the distribution of the heights of the female college students.
(d) The original data is measured in inches whilst the hand span was measured in centimetres. The data for both height and hand span should both be in the same units.
a. Using Excel, convert inches to centimetres.
b. Based on this recalculation, describe the distribution of the heights of the female college students.
Question 4  A teacher has noticed that even though attendance is no a component of the grade of the class, students who attend regularly obtain better grades. In fact, 40% of those who regularly attend class receive A's. whilst only 10% of those who do not regularly attend class receive A's. About 70% of students regularly attend class.
Answer the following questions (give all your answers to 1 decimal places):
(a) What is probability of students who receive A's given that they regularly attend class?
(b) What is the probability of students who receive A's given that they do not regularly attend class?
(c) What is the probability of students who receive A's?
(d) Are the events students regularly attend class and receiving A's independent? Explain why or why not.
Question 5  A study is done to compare side effects for those taking a drug versus those taking a placebo. One hundred randomly selected subjects are given the drug, and another 100 randomly selected subjects are given the placebo. Results are shown in the Table 2.
Table 2:

Headache

Yes

No

Drug

10

90

Placebo

5

95

Answer the following questions (give all your answers to 1 decimal places):
(a) Calculate the risk of getting a headache when taking the drug.
(b) Calculate the odds of getting a headache when taking the drug to not getting a headache when taking the drug.
(c) Calculate the relative risk of getting a headache when taking the drug compared to when taking the placebo.
(d) Calculate the odds ratio for getting a headache when taking the drug compared to those taking the placebo.