1. A method of operating a network, the method comprising the steps of: a) analysing a first datastore comprising data representing historical network performance; b) creating one or more indices within the first datastore; c) creating one or more probability networks in accordance with one or more of the indices created in step b); d) determining from the one or more probability networks a conditional probability associated with an alarm event; and e) if the conditional probability determined in step d) is less than a threshold value, disregarding the associated alarm event; or f) if the conditional probability determined in step d) is greater than a threshold value, using the associated alarm event in conjunction with other historical network data to predict future alarm events.