Introduction to Statistical Methods for the Life and Health Sciences
Instructor: Ivo Dinov, Asst. Prof.
Departments of Statistics & Neurology
Friday, Jan. 24, 2003
Please, submit your homeworks after class on the due date. See the
HW submission rules.
On the front page include the following
(HW_2_1) Backpacks are commonly seen in many places, especially
university campuses, schools, shopping malls and airplanes. In 1997, a
US consumer magazine conducted a study on backpacks. Some of the data from
the study is reproduced in the table below. The price of the backpacks
is to the nearest US dollar, volume is measured in cubic inches and number
of books is the number of 5-inch by 7-inch by half-inch books that the
backpack easily holds.
Calculate the average volume used per book (i.e. the volume divided by
the number of books) for each backpack.
Following the guidelines for tabular presentation (Section 2.2.2 of the
text), redraw the table with the information from (a) added to it.
Note: Assume that we are primarily interested in the price of the backpacks.
Add averages to the table as appropriate.
You may use Stata to draw the table.
Use either Excel or Stata to create three separate scatter plots – volume
vs price, number of books vs. price and number of books vs volume. Print
out the three plots. Note: Each axis of the plots should be appropriately
labelled. If possible, try to print the three plots on one sheet of paper.
Write a short report (from 150 to 250 words) about the data. Your report
should include a discussion on the data (comments on trends, problems or
interesting features in the data and what other data could be collected
to help consumers compare backpacks) and a recommendation for consumers
(which backpack(s) do you recommend buying and why). Are we missing
some factors that may effect our purchasing decision? If so, give examples.
|Number of Books
(HW_2_2) Describe/Address the following terms in your own words:
Sampling and Non-sampling errors
Give two examples of each of the three basic ways for data collection (surveys,
designed experiments and observational studies).
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Ivo D. Dinov, Ph.D., Departments of Statistics and Neurology,
UCLA School of Medicine