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Second step with non-linear regression: adding predictors

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In this post we will see how to include the effect of predictors in non-linear regressions. In other words, letting the parameters of non-linear regressions vary according to some explanatory variables (or predictors). Be sure to check the first post on this if you are new to non-linear regressions. The example that I will use throughout this post is the logistic growth function, it is often used in ecology to model population growth. For instance, say you count the number of bacteria cells in a petri dish, in the beginning the cell counts will increase exponentially but after some time due to limits in resources (be it space or food), the bacteria population will reach an equilibrium. This will produce the classical S-shaped, non-linear, logistic growth function. The logistic growth function has three parameters: the growth rate called “r”,…
Original Post: Second step with non-linear regression: adding predictors