> My point would be that while SpaceX does save lots of money, it doesn't do so by producing cheap or less reliable rockets
Indeed, if we assume that the each launch is an IID binomial coin flip (which isn’t really the right way to evaluate right-censored data), and observe (by reading Wikipedia) that SpaceX has had at least 450 successful Falcon 9 launches since the last in-flight failure, then they have at least five nines of reliability:
0.999995^450 ~= 449/450.
Which appears to be an industry-leading stat.
For context (excluding the Columbia re-entry failure), the space shuttle only had 4 nines:
I'm going to challenge those numbers: Using a posterior probability density function for a binomial distribution, the lower bound in Falcon 9 reliability is .9934 with 95% confidence (assuming 450/450 successful trials). The reliability of F9 could be much lower than five 9s and still reasonably give you 450/450 successful trials. There's only a 0.44% chance that F9 reliability is at least five 9's given the data.
Indeed, if we assume that the each launch is an IID binomial coin flip (which isn’t really the right way to evaluate right-censored data), and observe (by reading Wikipedia) that SpaceX has had at least 450 successful Falcon 9 launches since the last in-flight failure, then they have at least five nines of reliability:
0.999995^450 ~= 449/450.
Which appears to be an industry-leading stat.
For context (excluding the Columbia re-entry failure), the space shuttle only had 4 nines:
0.99994^125 ~= 124/125