Look at the left column of the "Methodolgies of Science" diagram below. This is probably the part of the scientific method with which you are most familiar. We will NOT experiment on real populations in this unit, rather we will use compuatational models.


©Ken Flurchick 2000

We will focus on the middle and right columns of the diagram above. The model we will use has already been constructed for you. The theory used to make the model is that only the birth rate, death rate, immigration rate, and emigration rate affect the size of the population.

The model we will use was made with a mathematical modeling program called Stella. The diagram below shows a square representing the size of the population of Alaska in 2000. The arrows with the circles and valves represent the four rates that affect the size of the population of Alaska. What are these four rates?

Two of the arrows point into the square of the population, showing that these add to the size of the population. The other two arrows point out of the square, showing that these take people out of the population. Which two rates are involved with an increase in the population? Which two rates are involved with a decrease in the population?