Then use that as one of the four critical parameters.
E.g.: You might believe that some variability in conditions (hot-house Earth, iceball Earth) is required to "kick start" evolution. Okay, then simply pick out the subset of the parameter space with that amount of variability.
But we literally don't know the variability. Unlike the numbers of stars in the universe or the number of planets, which we have some statistically board observational evidence for, we have no such statistical evidence for the development of high energy microbiology. We have 1/1 examples. And we don't know if that's because it was inevitable and the eukaryotes have just outcompeted everything else or if it was exceedingly rare. It could be a coefficient of effectively 0 on the whole the thing.
E.g.: You might believe that some variability in conditions (hot-house Earth, iceball Earth) is required to "kick start" evolution. Okay, then simply pick out the subset of the parameter space with that amount of variability.