>But my point was you cannot look at a historical event and say "Well this happened, so that was the chance."

If the event happens repeatedly, you absolutely can! If someone attempts something 20 times, and it works 10 of them, you can conclude that there's an approximately 50% chance of success. You have a sample size! The exact same thing is true for a statement like "the chance of an astronaut dying is approximately 1 in 25". We have the sample size to show that.

>That's the basis for the silly internet joke "The chance is 50/50, either it happens or it doesn't."

No, that's totally different. That's a misunderstanding of priors. What you're doing is more like forgetting that the law of large numbers is a thing.

I’m not forgetting anything. The actual shuttle missions were not a statistical experiment or a consistent action where you can say “well this is what happened so that was the chance of death on an individual shuttle flight.”

It only means that’s your chance if you have the technology from quantum leap (the tv show) and you randomly land in the body of one of the participants.

as I said already the shuttle and everything around it evolved. The crews changed. Trying to say “the actual chance of death was this based on how many people died.” is silly.

>It only means that’s your chance if you have the technology from quantum leap (the tv show) and you randomly land in the body of one of the participants

No, then the event already happened, so you know the outcome with certainty.

> The actual shuttle missions were not a statistical experiment or a consistent action where you can say “well this is what happened so that was the chance of death on an individual shuttle flight.”

Indeed there are confounding factors that make the error nontrivial. This doesn't invalidate the entire experiment.

>Trying to say “the actual chance of death was this based on how many people died.” is silly.

Its exactly as silly as saying "the actual chance of getting heads is based on how many heads you get". The problem with your argument is that that isn't silly. To calculate how likely getting heads is, you flip the coin a bunch of times, see how many heads you get, and then you have your answer (and a confidence level). Its the opposite of silly.

In other words, there's no big difference between "We'll flip a bunch of coins to see how likely we are to pull heads" and "we'll launch a bunch of people into space to see how likely they are to end up dead". The second isn't as rigorously controlled as the first, but that's fine as long as you account for it.

I think the difference is the scope of the problem. A coin flip is a deterministic, known event with two possible answers in most situations.

A rocket or space shuttle launch is like a thousand coin flips, where any one result, sequence of results or other combination of events results in death. As an added bonus, any number of unknown external events, from Ambient temperature, to bird strike, to sabotage can render the model useless and kill you in some unforeseen way.

The scope is different, but the principle is the same.

Say you launch your rocket 50 times, out of which 3 times it explodes - first time because of a bird, second time because of the legendary ULA Sniper, third time because of internal problems. That 3/50 is still closer to the truth than just assuming "I really don't know" (1/2) or refusing to answer the question - it has huge error bars, but implicitly captures some of the phenomena that make launches go wrong.

That's a great point.

My perspective was probably a little impacted from spending the first truly beautiful day of the summer dealing with a failed "high availability" system. :)