Garden with Insight v1.0 Help: empirical/theoretical

An empirical model is one based primarily on observation. An empirical model uses functions that best fit existing data to predict future values -- it is data- centric. For example, if you notice that your tomato seedlings are wilting and want to make an empirical model about it, you might remember that last year this happened and that watering the plants brought them back. You don't necessarily care why watering the plants restored their health: you only care that it worked.

A theoretical model is one based primarily on what are called first principles, or scientific laws that have been created by theorizing and testing ideas about how some process works. An empirical model uses functions that best fit existing explanations to predict future values -- it is idea-centric. For example, if you want to make a theoretical model about why your tomato seedlings are wilting, you would consider all of the reasons tomatoes wilt and decide that the most likely problem (from the relative importance of all the causes) is that they are lacking in adequate water.

Of course models can have both empirical and theoretical aspects, and there is a broad range between these two extremes. EPIC (the model on which this simulation is based) is mainly empirical. The parameters for the many S curves that drive the simulation are based on published experiments, not on theories (though they may mesh with theoretical explanations). EPIC bases its predictions on results, not on reasons. Most models that cover this broad a range are empirical, because the processes involved are very complex. Theoretical models tend to examine a much smaller phenomenon, such as only photosynthesis or only ground water flow.