The first question in the series, with more explanation, is here
The model in question uses probability distributions over seven input parameters.
In this case we will be assessing the seventh parameter in the Drake's Equation, .
It is the average length of time, in years, that civilizations capable of being detected remain detectable.
It could be very short since the technology for radio and nuclear weapons emerge fairly close together. It could also be very long if a civilization (even a relatively short-lived one) were to release a lot of later-detectable and widespread artifacts.
The resolution to this question will be the scientific consensus 100 years from now, regardless of any remaining uncertainty.