STAT 13

(Sec. 1a-1c)

Introduction to Statistical Methods for the Life and Health Sciences

Instructor: Ivo Dinov, Asst. Prof.

Departments of Statistics & Neurology

http://www.stat.ucla.edu/~dinov/

Due Date:

See the HW submission rules. On the front page include the following header.

(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.

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.

Outlier
Skewed Distribution
Sampling and Non-sampling errors
Give two examples of each of the three basic ways for data collection (surveys, designed experiments and observational studies).

\Ivo D. Dinov, Ph.D., Departments of Statistics and Neurology, UCLA School of Medicine/