[Model function for population rhythm using wavelet transform]

Interindividual variability among a population induces some chronobiological analysis difficulties; to solve them we create a so called Model Function, which is associated to a biological rhythm. This model function is an image of a population and can be used directly for further studies. Its building has several steps: normalisation, wavelet transform, threshold application, summation of transforms and inverse wavelet transform. This algorithm is tested on activity rhythm of four inbred mouse strains: B, C, BC and CB; this has permitted to check that F1s have an heterotic effect and that this acrophasis indicates a B dominance. The Model Function permits to deal with some difficult problems, such as rhythm shape and position of a population acrophasis. Those elements are absolutely necessary in chronotherapy which needs the knowledge of maximum efficacy and toxicity hours.