FW3200 – Biometrics and Data Analysis Homework No. 4 – Tests of categorical data
Categorical data are data that fall into discrete categories and can’t be subdivided quantitatively. For
example, trees can be “alive” or “dead” and there’s nothing in-between. Analyzing categorical data
involves the Chi-square reference distribution.
Find the solutions to the questions on the following page using Microsoft Excel. Submit your answers in a
professional memo. For each question, summarize the appropriate statement or value to go with the six
Summarize your results, including any tables or figures, in a professional memo no longer than one
double-sided page. Include a very concise description of your procedure. Professionalism counts!
You must put your Lab Section on your memo and address the memo to your TA.
This assignment is due at the beginning of class on Friday, 15 February 2013.
Unless otherwise specified, use α = 0.05.
ONE: Jim Rivard performed an accuracy check on field plots installed by FW4810 “Capstone” students
last fall. He expected that the failure rate would be 1 in 10. After field checks, 309 plots received a “pass”
and 47 received a “fail”. Use a G-test to see if the results are congruent with his expectation.
TWO: Some creative professor proposed a Perspectives class in which the social, health, and criminal
effects of marijuana consumption was the focus. At the beginning of the class, the students were polled to
ascertain their perspective on how possession should be treated legally. The proportions were: 7%
favoured legalization, 18% favoured decriminalization, 65% favoured the current laws, and 10% had no
opinion. At the end of the semester, the students were polled again and the results obtained are shown
Use a G-test to see if the Perspectives class had an effect on the students’ perspective. Use α = 0.01.
THREE: The drug Tamoxifen is thought to slow tumor growth in patients with breast cancer, and may
also protect against heart disease. Data from a study on the drug are shown below. Is there an effect of
treatment on heart-related deaths? Does Tamoxifen decrease overall deaths in patients?
Page 1 of 2 FOUR: One of the classic tests of natural selection involves release of two different forms of the
peppered moth. One is mostly white, while the other is dark. Scientists assumed that the light form
evolved to blend with lichen that grows on tree bark in unpolluted areas. The theory is that the dark form
evolved in cities where pollution resulted in lichen-free trees. As a test, moths were released in two areas,
one in a city and the other in an unpolluted forest, and recaptured with traps. Analyze the data, below.
FIVE: We know that at MTU that Pepsi outsells Coke at a 60:40 ratio. We surveyed FRES students and
obtained additional data (below). Students in the program reported their gender, pet preference (c=cat,
d=dog), beverage preference (c=Coke, p=Pepsi) and the number of syl ables in their given name.
(1) Is there any cola preference in FRES? (2) Is there a gender difference in cola preference? (3) Is there
a gender difference in pet preference? (4) Is there a gender difference in syllables in given names?
Note: Some questions in this Homework were adapted from Gould and Gould (2002) “Biostats Basics”.
Page 2 of 2
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Pathogenesis of and immunity to melioidosis Department of Microbiology and Infectious Diseases , Uni 6 ersity of Calgary Health Sciences Center , Calgary , Alta , Canada T 2 N 4 N 1 Abstract While Burkholderia pseudomallei , the causative agent of melioidosis, is becoming increasingly recognized as asignificant cause of morbidity and mortality in regions to which it is endemic, no l