Alert only when all locations reporting response time above threshold

Alert only when all locations reporting response time above threshold

I'm being inundated with alerts because one or two sites are above a threshold for response time. I'd like to change it so that ALL sites must be over a threshold.

I prefer this because if one or two out of eight sites are reaching my site slowly, but all others are just fine, there is likely little I can do, as it is probably caused by circumstances beyond my control.

Is there a way to do this?

Thanks!