Think of the "Last-Value Threshold" value as a flag raiser. If the average bandwidth usage since the last test exceeds the Last-Value Threshold, a flag goes up and it then verifies the Short-Term Threshold. The Short-Term value is basicaly the sum of the average bandwidth usage values gathered by each test within the "Sample Size" time and the total is then divided by the number of tests within that sample size. This would make it the average of the averages. If this value is greater than the Short-Term Threshold, the Monitor fails. If this value is lower than the Short-Term value, the Monitor stays green until the next test.
This entire mechanism is to prevent the Monitor from failing and alerting you because of a short spike.
Does this help?
Thanks, I think this does help.