University of Toronto Scarborough
STAB22 Midterm Examination
March 2009
For this examination, you are allowed one handwritten letter-sized
sheet of notes (both sides) prepared by you, a non-programmable,
non-communicating calculator, and writing implements.
This question paper has 14 numbered pages; before you start,
check to see that you have all the pages. There is also a signature
sheet at the front and statistical tables at the back.
This examination is multiple choice. Each question has equal
weight. On the Scantron answer sheet, ensure that you enter your
last name, first name (as much of it as fits), and student number
(in “Identification”).
Mark in each case the best answer out of the alternatives given
(which means the numerically closest answer if the answer is a
number and the answer you obtained is not given.)
Before you begin, check that the colour printed on your Scantron
sheet matches the colour of your question paper. If it does not,
get a new Scantron from an invigilator.
Also before you begin, complete the signature sheet, but sign it
only when the invigilator collects it. The signature sheet shows
that you were present at the exam.
1
, 1. A random sample of 25 blood donors was given a blood test to determine their blood type. The pie
chart below shows the distribution of the blood types of these 25 donors. (Note: A, B, O and AB are
the blood types)
How many donors in this sample had blood type A?
(a) 10
(b) 15
(c) 5
(d) 18
(e) 20
2. Some researchers have proposed a new treatment for Alzheimer’s disease. They propose to divide their
subjects into two groups; one group gets this new treatment, while the other group gets the standard
treatment. At the end of the study, the quality of life of all the subjects is assessed.
What would you say about this study design?
(a) the researchers didn’t need to have a group of subjects receiving the standard treatment. They
could have obtained equally good results with half the number of subjects.
(b) the researchers could have used available data
(c) it enables the researchers to see whether the new treatment has more than a placebo effect
(d) this is a case where a comparative experiment is not necessary
(e) there is likely to be a nonresponse bias
3. In the study of Question 2, suppose that the researchers obtain statistically significant results, with
the new treatment offering a higher average quality of life. Are the researchers entitled to conclude
that the new treatment is a cause of a higher quality of life?
(a) yes, because the results come from an observational study
(b) no, because the results come from an observational study
(c) yes, because the results come from a statistical experiment
(d) no, because the results come from a statistical experiment
2
STAB22 Midterm Examination
March 2009
For this examination, you are allowed one handwritten letter-sized
sheet of notes (both sides) prepared by you, a non-programmable,
non-communicating calculator, and writing implements.
This question paper has 14 numbered pages; before you start,
check to see that you have all the pages. There is also a signature
sheet at the front and statistical tables at the back.
This examination is multiple choice. Each question has equal
weight. On the Scantron answer sheet, ensure that you enter your
last name, first name (as much of it as fits), and student number
(in “Identification”).
Mark in each case the best answer out of the alternatives given
(which means the numerically closest answer if the answer is a
number and the answer you obtained is not given.)
Before you begin, check that the colour printed on your Scantron
sheet matches the colour of your question paper. If it does not,
get a new Scantron from an invigilator.
Also before you begin, complete the signature sheet, but sign it
only when the invigilator collects it. The signature sheet shows
that you were present at the exam.
1
, 1. A random sample of 25 blood donors was given a blood test to determine their blood type. The pie
chart below shows the distribution of the blood types of these 25 donors. (Note: A, B, O and AB are
the blood types)
How many donors in this sample had blood type A?
(a) 10
(b) 15
(c) 5
(d) 18
(e) 20
2. Some researchers have proposed a new treatment for Alzheimer’s disease. They propose to divide their
subjects into two groups; one group gets this new treatment, while the other group gets the standard
treatment. At the end of the study, the quality of life of all the subjects is assessed.
What would you say about this study design?
(a) the researchers didn’t need to have a group of subjects receiving the standard treatment. They
could have obtained equally good results with half the number of subjects.
(b) the researchers could have used available data
(c) it enables the researchers to see whether the new treatment has more than a placebo effect
(d) this is a case where a comparative experiment is not necessary
(e) there is likely to be a nonresponse bias
3. In the study of Question 2, suppose that the researchers obtain statistically significant results, with
the new treatment offering a higher average quality of life. Are the researchers entitled to conclude
that the new treatment is a cause of a higher quality of life?
(a) yes, because the results come from an observational study
(b) no, because the results come from an observational study
(c) yes, because the results come from a statistical experiment
(d) no, because the results come from a statistical experiment
2
