Energy spectra and chemical composition of the primary cosmic ray nuclei for energies higher than 1 PeV are obtained mainly from measurements of intensities and various properties of extensive air showers. Additional and importent data from the study of gamma ray families are available in addition. In bouth cases we have informations from the range of very high fluctuations. An importent fact that we are working with the very steep primary energy spectra has to be taking into account. In this research different probability distributions have been used as well as their convolutions with power primary spectrum.The role of the influence of different parameters on the measurements of primary spectra will be discussed in the paper.

Proceedings of the 30th International Cosmic Ray Conference; Rogelio Caballero, Juan Carlos D'Olivo, Gustavo Medina-Tanco, Lukas Nellen, Federico A. Sánchez, José F. Valdés-Galicia (eds.); Universidad Nacional Autónoma de México, Mexico City, Mexico, 2008; Vol. 2 (OG part 1), pages 145-148