Back to our problem of trying to predict the future, or at least the future population of some
species in some region. Two ideas for how to do this come to mind.
The first is to look at the historical data and see if we can identify trends. This is a
great idea, but is often very difficult. Data seldom fits a simple pattern perfectly and we
must constantly worry about what trends are “real” in the data, what trends are due to
temporary changes in the situation and what trends are created by our human desire to see
patterns, even when there are none.
The other idea is to try to make a deterministic model of the population that is based
on some basic assumptions of how the population changes. We need a model that is simple
enough to use, but complicated enough to give an at least approximately reliable predictions.
The first idea requires we be able to interpret data from a complicated noisy world so we
need techniques and expertise in statistics (stay tuned!). So for now we follow the second
idea and construct models based on some (simple) assumptions about biology. Of course,
combining both model building and data analysis–using the data to motivate and check the
assumptions and using the models to tease out trends in the data–is more powerful than
either technique by itself.
Think of this section as practice building models for physical world and seeing what kinds
of behavior simple models can predict. The “hidden” agenda is to use some of the functions
we have seen in our zoo.