Apologies just saw this now since we were taking a break! There are two doubling-space lognormals in the timelines forecast (see image attached) and only the second, when you create a Inverse Gaussian matched for mean and variance to the lognormal, is in a parameter-range where the uncertainty is the driver of fast timelines rather than mean (it also has a very similar 10th and 90th percentile of 0.44 months and 18.7 months).
I do think speeding up to the second lognormal is not super well justified, but fine to ignore disagreements on parameter central tendencies (it’s kinda odd to say speeding-up because the mean actually gets slower while the median gets somewhat faster and the sub-median gets wildly faster (5x faster at the 10th percentile)).
I actually think adjusting this will make fast timelines significantly more appealing to people looking into the model because a big “what?” issue for me at least is how much mass implies we already have or are about to have SC in the timelines model, so adjustments that keep the median fairly close but sharply curtail how fast the 10th percentile are in the model would make me update to trust the model more (and thus believe a <2030 SC timeline more).
Apologies just saw this now since we were taking a break! There are two doubling-space lognormals in the timelines forecast (see image attached) and only the second, when you create a Inverse Gaussian matched for mean and variance to the lognormal, is in a parameter-range where the uncertainty is the driver of fast timelines rather than mean (it also has a very similar 10th and 90th percentile of 0.44 months and 18.7 months).
I do think speeding up to the second lognormal is not super well justified, but fine to ignore disagreements on parameter central tendencies (it’s kinda odd to say speeding-up because the mean actually gets slower while the median gets somewhat faster and the sub-median gets wildly faster (5x faster at the 10th percentile)).
I actually think adjusting this will make fast timelines significantly more appealing to people looking into the model because a big “what?” issue for me at least is how much mass implies we already have or are about to have SC in the timelines model, so adjustments that keep the median fairly close but sharply curtail how fast the 10th percentile are in the model would make me update to trust the model more (and thus believe a <2030 SC timeline more).