I beleive I have found a method to do this. If I use the following expression, it seems to work.
avg_check1 assert mod=nch expr = "avg((abs(V(g,s)) > 2.0) )" level=error max=0.01 message="Signal Overvoltage too high"
However this does not generate an error in the ADE violations display. It shows up in the spectre log, but not violations display.
The following check does end up in the ADE violations display
avg_check2 assert mod=nch expr = "(abs(V(g,s)) > 2.0) " level=warning message="Signal Overvoltage too high"
The difference is one is evaluated during the tran simulation and one is evaluated after the sim is over. Is there a setting to allow assertions calculated at the end of the analysis toend up in the ADE violations display?