By the help of a derivative-free search method (differential evolution), the parameter estimation for a nonlinear regression function (binary logistic regression) is carried out. Random data material is available: Depending on the volume x (x=0 "very quiet" to x=5 "very loud") the ringing of an alarm clock leads to the fact that one "continues to sleep" (category y=0) or "wakes up and get up"(category y=1). It can happen that a quieter ringing is already heard and a louder ringing is not heard. The example is suitable for school mathematics and shows connections to the theory of probability.