How do you calculate the births flow in a simple deer population model?

Conditions

• The model assumes births are proportional to the current population.
• The birth fraction is a constant parameter representing the proportion of the population giving birth per time period.

Reasoning, step by step

1. Identify the current value of the 'Deer' stock.
2. Identify the value of the 'Birth_fraction' parameter.
3. Multiply the stock value by the parameter value.
4. Assign the result to the 'Births' flow.

Example

If the initial deer population is 100 and the birth fraction is 0.2, the births flow is $100 \times 0.2 = 20$ deer per year.

Common misconceptions

• Adding the birth fraction to the population instead of multiplying.
• Assuming the birth fraction changes based on the population size in this simple linear model.
• Confusing the birth rate (fraction) with the total number of births.

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Explore next

• How do you calculate the deaths flow in this model?
• What happens to the population if births exceed deaths?
• Why is the birth fraction modeled as a constant?