Comparison of Six Sigmoid Growth Curve Models
Comparison of Six Sigmoid Growth Curve Models
Experimental sigmoid growth curves approaching an asymptotic level have been described by a variety of mathematical expressions having three adjustable parameters. Among them are the Gompertz model, various versions of the logistic equation, and the cumulative form of the Weibull ("stretched exponential") model. Despite their different mathematical formulations, most of these models can be used interchangeably, that is, they have a similar degree of fit as judged by statistical criteria. This is demonstrated by allowing the user to generate growth data with any of six growth models and fit the data using nonlinear regression with any of the models for comparison.