1. A method of scheduling tasks to be performed by means of a plurality of resources, comprising: providing schedule data ( 26, 42 - 45 ) corresponding to schedules of the tasks ( 11 ) that individual ones of the resources are to carry out, prepared from task data ( 4 ) concerning the tasks to be carried out and resource data ( 6 ) concerning characteristics of resources available to carry out the tasks over a given period, together with contingency values (C) associated with the scheduled tasks for the individual resources.