Task4 (WG-T4) deliverable of the INGV-T4 Research Project 2015-2016 "HYbrid ground motion prediction equations for PSha purposes: the study case of souTHERn Italy". The HYPSTHER project is devoted to develop a methodological approach to retrieve ground motion prediction models for Southern Calabria and Sicily, based on the integration between recorded and synthetic data. The WG-T4 deliverable is devoted to combine all the products from other tasks and to perform a series of sensitivity studies on models and/or parameters to evaluate their impact on the seismic hazard assessment.