Demographics
Questions

Note: These questions are not your written assignment to hand in. Do as little or as much of this as you please.

  1. Please fill in the following table by reading the bases of the pyramids after running each Scenario. The "original" pyramid is the one at the bottom. The top pyramid has the same fertility rates, just shifted 5 years later in life.

    Country Growth rate (%)
    original    		 Children per woman
    original    		 Growth rate (%)
    new (shifted)    		 Children per woman
    new (shifted)
    USA        
    China        
    Egypt        
    Germany        
    India        
    Italy        
    Mexico        

  2. Based on your table above, for which countries does shifting reproduction five years decrease the population growth rate r? Increase? Explain. Does shifting reproduction have any effect on the number of children per woman?

  3. Let's play hoops. Select Scenario | USA. Notice that the blue line, the official US Census projection to year 2050, goes up in a straight line. Yet the purple line, our simulation with current rates, takes a sharp bend and goes flat. Use the change rates menu to get the purple line closer to the blue line. Hint: Set "shift" and "mortality" changes to zero and instead adjust the fertility rate.

  4. Based on the previous question, what do the demographers at the US Census Bureau expect to happen in the US, if they base their projection on only the current population? What do they expect if they are basing their projection on immigration?

  5. For the US, decrease mortality by -100%. That means, nobody dies until age 95, then they all die. Zooming in on the plot (see above), how much difference does this change make in the population by 2090?

  6. Repeat the previous question, except increase mortality by 100%. This doubles the death rate per cohort. How much difference does this change make in the population by 2090?

  7. What do you think it would take for mortality to control population growth? Please think about it, and then read the file on HIV/AIDS.

  8. Let's look at time delays. Select Scenarios | Egypt. On the change rates menu, set shift fertility years to 0, and fertility rate to -28 (decrease fertility 28%). What is the time delay before Egypt's population stops growing? You may want to restart and step through this to see how the rate r changes while the avg children per woman is at replacement level reproduction.

    How many people are added between 2005 and when the population crests? Explain in your own words why the population keeps growing after it reaches replacement level reproduction, and how long it takes for that change to bring growth to zero.

  9. Select Mexico or Egypt. Find rate changes that mimic the blue Census Bureau projection.

  10. It is a commonplace in Egypt not to register children, especially male children (to avoid the military draft.) Invent a population projection to compensate for this undercounting.

  11. There isn't a lot of industry in Egypt. The people of Cairo seem underemployed. What do you think becomes of extra people? What do they do? Where do they go?

  12. Select Germany or Italy. Find rate changes that mimic the blue Census Bureau projection.

  13. You'll notice that the projected pyramids have a nice smooth shape, but the original pyramids are ragged. Feast and famine, war and disease take their toll on a people. Find the traces of World War II in Germany and the US. Use the restart button to study the pyramids now, since the WWII fighting generation is already 75+ years old.

  14. What is the shape of a growing population pyramid? A declining one? A stable one?

  15. Select China. China instituted strict population control measures some years ago. When do you think that was? (Hint: look for wobbles in the blue line.) How many years are there between that new policy, and the population growth stopping? How much does the population increase during that delay? Notice the number of children per woman is the same at the start and end of that simulation.

  16. Try relaxing China's strict population control, to replacement reproduction levels instead of below replacement. To do this, set shift fertility age to 0.0 and change fertility rate to 29.5 (increase by 29.5%). This doesn't add very many years to the delay before the population stops growing (how many years?) How many more people does it add? Compare that number to the other country populations on the list.

  17. China is the most populous country in the world. When will India's population outstrip China's?

  18. Between now and 2050, India's population is projected to grow by 520 million people. That's nearly twice the population of the US. The total will be about three and a half times the current size of the US. They would probably like to live as well as we do. What happens if they get their wish?

  19. Let's look at workforces in the demographic pyramids. People aged 20-60 form the economic backbone of a society. Other ages are less able to work. Look at the following pyramid for Italy in 2050. Figure out how many people there are in the young, the workforce, and the old categories. You can count just females if you wish. (Counting just males will underestimate the old.) Add the young and old together, and divide by the workforce. This is how many people, in addition to themselves, each workforce member is supporting.

  20. If you wish, you can repeat this for some other country and read the pyramids at http://www.census.gov/ipc/www/idbpyr.html.

  21. For this calculation, I get about a 1.16 nonworker/worker ratio for the US for 2025, just before the Social Security system expects serious shortfalls. I get 1.12 for China in 2050 doing that same calculation. From this perspective, compare the situations of these two countries.

Ginger Booth, revised March 2005, orig. December 2000, for oswald.schmitz@yale.edu