Dose-response curves are use used to describe the relation of dose (e.g. of a pharmaceutical) and the resulting effect. To do this, dose response functions are fitted to measured data. These functions can then be used to calculate of important benchmarks such as the EC50 (dose leading to 50 % effect).
A number of standard dose-response functions are commonly used. Some of these were designed for so called quantal data, which means that the effect is based e.g. on the number surviving (example for quantal data: From 10 animals 18 survived). Other dose-response functions are used for continuous data, which means that the effect is a continuous variable, such as body weight or blood pressure.
In GSS a number of dose response functions are available and for each of them there is a description of the meaning of parameters and when to apply which function.
To decide whether or not a fit with a function is good enough, well established measures for the goodness of fit (e.g. R²) are used and in addition confidence intervals or confidence bands are provided.