Exploring Growth Factors in Population Data

How and why populations grow is a key question in environmental science. In this exercise, you examine and graph current world population data to explore which factors most strongly correlate with birth rates. Go to www.mhhe.com/apps.

There you will find an Excel data file named popdata.xls. Double-click on the file name to copy it to your hard disk. If you have Excel on your computer, you should be able to open the data file by double-clicking on it. (Other spreadsheet programs can also read this file, but you must open it from within your program, not by double-clicking.)

1. This file contains population data for the countries of the world, sorted by the United Nations Human Development Index (HDI) rank. First look at the top 20 countries. Where are they? What is the range of income levels (in GNP per capita) of the top 20? What is the range of income for the bottom 20 countries?

2. Now make an X,Y scatter graph of Adult Literacy and Birth Rate. (Detailed instructions for making graphs in Excel are included at the far right side of the spreadsheet page [column N].) How would you describe the relationship between these variables? How would you explain this relationship? Keep this graph in your spreadsheet while you make three more scatter graphs: (1) GNP per Capita and Birth Rate, (2) Life Expectancy and Birth Rate, and (3) Infant Mortality and Birth Rate. Describe the trends you observe, and explain what they mean.

3. How would you compare the relative amount of scatter in each of your graphs? Why do some curves slope from right to left, while others slope in the opposite direction? If you draw a line through the middle of the dot cluster, some curve smoothly, while others seem to have a break or inflection point. How would you interpret these patterns?

4. Try changing the shape of your graphs. (See instructions on the right side of the spreadsheet to do this.) How does making the graphs taller or wider affect the way your trends look? How could you deliberately manipulate the graph shape to affect other people’s interpretation of the data? Is this ethical? Have you ever seen it done?

5. Now make a dot graph of GNP Per Capita and Adult Literacy. Is there a linear relationship between the two variables? Why or why not?