Chapter 8

Population Comparision

Back to List | Introduction | Population |  Salary Fairness | Superstition | Exercises

Introduction

This project expands on the previous project by including a second population in each hypothesis test, thereby allowing you to draw conclusions based on comparisons of two groups. First you must familiarize yourself with the data to be used.

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Population

When thinking about population statistics, a good place to start is the U.S. Census Bureau http://www.census.gov. On that main Web site, you'll find a link to People-Estimates. We are interested in national population statistics as characterized by age. These can be found in a table located at

http://www.census.gov/population/estimates/nation/intfile2-1.txt

Once there you will see an easy-to-read table of population estimates by age group from 1995 and later. This table will be important in the exercises.

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Salary Fairness

The Web site for the U.S. Census Bureau also contains a great deal of income data. Go to the page of historical income data

http://www.census.gov/hhes/income/histinc

and study the Table which summarizes mean income by sex for people of all races for the entire United States. Isolate the 1998 data and be sure you understand the meaning of the data prior to the exercises.

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Superstition

Is Friday the 13th unlucky? Regardless of your feelings for superstitions, it is possible that Friday the 13th could have a significantly different number of accidents and mishaps than other days. For example, superstitious folk, convinced bad things are going to happen that day, may cause accidents, thereby fulfilling their own prophecy. On the flip side, some people may be especially careful that day, causing a reduction in "bad luck" from other days. Let's see what we can find out.

A data set can be found at the Data and Story Library site ( http://lib.stat.cmu.edu/DASL) by searching for Friday the 13th materials. Find this data set now.

The data were collected in an effort to study various aspects of human behavior on Friday 13th by monitoring the change in traffic patterns between Friday the 6th and the subsequent Friday the 13th along with shopping traffic and accident reports. Be sure you understand the data arrangement before proceeding to the exercises below.

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Exercises

When you've completed each exercise, click "Submit for Grade" in order to submit your answers to your professor.

1.  

Has the percentage of senior citizens (age 65 or older) changed between 1995 and 1998? Justify your answer with statistical methods.

2.  

Based on the income data you found at the Census Bureau site, do you believe men are paid significantly more than women? Use a standard deviation of $10,000 for each group and an appropriate hypothesis test.

3.  

Use the data in the accident category from the Friday the 13th data file, along with an appropriate hypothesis test to answer the question: Is Friday the 13th any more unlucky than Friday the 6th?

4.  

Do more people shop on Friday the 13th? Justify your answer by formulating and executing a hypothesis test.

   


© 2000 by Addison Wesley Longman
A division of Pearson Education