1. A method of evaluating events in a telecommunication network, said events occurring in relation to operation of the telecommunication network, and said method comprising: defining a set of quantized values for each of two or more event parameters that are associated with events of a certain type; implementing a counter per conjunction, for one or more conjunctions of the sets of quantized values, each conjunction being one of the unique combinations of quantized values possible among the sets of quantized values; detecting occurrences of events of the certain type; and for each detected occurrence: for each of the two or more event parameters, quantizing an actual value of the event parameter, as measured for the detected occurrence, into a corresponding one of the quantized values in the set of quantized values defined for the event parameter; and responsive to determining that the quantized values of the two or more event parameters match one of the conjunctions for which a corresponding counter is implemented, incrementing the counter corresponding to the matched conjunction; and outputting counter values from the per-conjunction counters, for use in a performance monitoring system associated with the telecommunication network.