> actual number of successes vs partial successes vs launch failures vs fatalities are the best data we have
Current vehicles are vastly different from the originals. What we’re trying to do is predict the probability of the next launch failing. Equally weighting far historicals and recents is bogus statistics.
> What we’re trying to do is predict the probability of the next launch failing.
I thought we were comparing methods. Unless the next payload is yours then the odds of the next launch failing is meaningless to most of us, but we can learn something from the methods used.
But sure, if you have a bet in Vegas or something then feel free try and calculate things as closely as possible. Just understand that several of Soyuz failures didn’t kill the crew so there’s other metrics people might care about.
What does this mean? The question most of us care about is which method resulted in a more reliable rocket. And SpaceX’s track record shines uniquely in that respect. The frequency, moreover, makes the results robust. Legacy rockets like Ariane will never reach that confidence because the likelihood of fluke successes won’t have been minimised when the rocket is retired.
As to why their methodology is important this isn’t the Falcon 9 this is a new launch system which is likely going to have multiple failures before it’s own streak can begin.
So sure, we can reasonably assume that Starship will get to a state of reliability similar to current Falcon rocket, eventually. We can’t assume the first few commercial Starship launches are going to even approach that level of reliability. And in fact the best point of comparison may be the early days of Falcon 9.
Speaking of methodology, it's incorrect to relate a development test result to reliability or risk. Source is my personal experience doing reliability calculations for a NASA rocket component and working with the statisticians incorporate my numbers into their risk model.
Current vehicles are vastly different from the originals. What we’re trying to do is predict the probability of the next launch failing. Equally weighting far historicals and recents is bogus statistics.