Lab 3: Demographics
Fill this sheet out and submit via the link given in Blackboard.
- Begin by going to the following website: https://www.learner.org/courses/envsci/interactives/demographics/
- Then click the link labeled Open Simulator.
- This will bring up a simulator, which is pre-loaded with demographic data from various countries.
Part 1. Population Growth and Age Structure Diagrams
Using the tool provided on the website, examine the 2015 population and the simulated 2050 population for the following three countries: USA, Brazil, and Nigeria. Don’t change any of the default settings for the country of interest. On the data sheet, record the population size and the population growth rate, and also match the overall profile of the age structure diagram to one of the reference shapes given below.
Also record the projected 2050 results, as follows. Without changing any of the default settings for the country of interest, click the Step button 7 times, which advances the simulation to the year 2050. (Each click of the step button advanced the simulation 5 years). Then, write down the projected population for 2050, as well as age structure shape that most closely matches the simulation. Record this information in the following data tables.
- Fill in the Data Tables.
|Data Table (2015)||USA||Brazil||Nigeria||What I’m looking for, for each row.|
|2015 Population||Population Size||321M||204M||182M||Population in 2015 at the start of the simulation. Looking for a number (in millions), e.g. 300 M.|
|Age Structure Shape||Shape 1||Shape 2||Shape 3||Shape of Age structure diagram in 2015 at the start of the simulation. Looking for a match to one of the reference shapes, e.g. Shape 3|
|Overall Growth Rate||0.78% annually||0.86% annually||2.65% annually||Growth rate in 2015 at the start of the simulation. Looking for a number expressed as a percentage, e.g. 1.3%|
|Data Table (2050)||USA||Brazil||Nigeria||What I’m looking for, for each row.|
|2050 Population||Population Size||321M||216M||462M||Projected population in 2050 from the end of the simulation. Looking for a number (in millions), e.g. 300 M.|
|Age Structure Shape||Shape 4||Shape 5||Shape 3||Shape of Age structure diagram in 2050 from the end of the simulation. Looking for a match to one of the reference shapes, e.g. Shape 3|
|Overall Growth Rate||-0.15% annually||-0.26% annually||2.84% annually||Projected growth rate for 2050, at the end of the simulation. Looking for a number expressed as a percentage, e.g. 1.3%|
Questions for Part 1
- What clues from the shape of the age structure diagram tell you whether a population has positive or negative growth rates?
The elements used to determine if the population has a negative or positive growth rate are the base and top. If the top is wider, the growth is considered negative and if the base is wider, the growth rate is considered positive.
- In our textbook, Figure 16.12 (p. 324) designates individuals in the ages of 0-14 as “pre-reproductive individuals”, and individuals between the ages of 15 and 44 as “reproductive individuals”. Explain how we can get some idea of whether a population is growing or shrinking by comparing the population levels of pre-reproductive individuals to reproductive individuals.
Usually, the pre-productive population group is determined on the basis that they have a higher growth rate as compared to the reproductive population. For instance, from the pictorial presentations, Nigeria serves depicts a scenario where the reproductive age is lower than the pre-reproductive age which is compared to diagram 3. Therefore, it is evidence that the generations are on a steady growth and reproductive edge.
Part 2. Population Momentum
Simulate what would happen if Nigeria were to suddenly have the birth rates of the United States. The step-by-step directions are as follows:
- Call up the information for Nigeria (which is growing at a high rate).
- Enter the editing menu for the vital rates of birth by clicking on the pencil that is shown in the vital rates chart. When you get into the menu for editing the birth rates, look at the “Use rates from ______” feature. Use the pull down menu to select the values for the United States (which has a lower birth rate).
- Click the Step button 7 times, which advances the simulation to the year 2050.
- As you go, watch the population size, the growth rate and the age structure diagrams,
- What happens to the population size immediately after the birth rate is abruptly dropped in this simulation?
From the simulation, if the birth rate is abruptly dropped, the population size instantly drops to -0.9% annually.
- After the birth rate went down abruptly, in this simulation, at what point in the future did the simulation show that the population size was leveling off or starting to decrease?
When the birth rate abruptly goes down in the simulation, in the year 2040, the population started to level off.
- Why doesn’t the population size drop immediately when the birth rate is thus diminished?
The reason as to why the population size does not drop immediately in case the birth rate is diminished is because the specific age group lives for several years before it starts to diminish.