bentarm comments on Amanda Knox: post mortem - Less Wrong
You are viewing a comment permalink. View the original post to see all comments and the full post content.
You are viewing a comment permalink. View the original post to see all comments and the full post content.
Comments (483)
Over the summer, Eliezer suggested (approximately, I am repeating this from memory) the following method for making an important decision:
This was essentially the method I used in coming to my (probably slightly low) estimate of the probability that Knox and Sollecito were innocent. It just felt like they were innocent, and I saw essentially no reason to suspect they were guilty. I will note that the 'pro-guilt' site that komponisto linked to was just horribly devoid of anything that I might consider evidence (if anything, that site did more to convince me of Knox's innocence than the pro-innocence site), and I did spend probably about 10 minute trying to find some evidence that they had missed, but completely failed.
On a different not, as I said at the time, 0.95 and 0.05 were just proxies for "pretty damn sure" and "pretty damned unlikely" - I have very little idea what 5% probability feels like, and I'm sure that if arbitrary scientific convention had settled on some different number for significance, I'd have picked that one instead. I have made some progress since a year ago on calibrating my estimates of small probabilities, but I absolutely do not think that I would be wrong approximately 1 time in 20 when making predictions to which I assign a probability of 0.95.
This is a better summary of what I said than what I actually said, so I hereby declare your distorted version to be my true teaching.
???
1d20!!!
I don't have an intuitive feeling for d20s, but it occurs to me that a useful resource might be a list of day to day events of certain probabilities so we can calibrate our intuitions to them.
Googling hasn't found me anything useful, could anyone give an example of an normal event that has a 5% chance of occuring?
You look at a clock and the seconds are :00, :01, or :02.
It is a little over the chance that if you are dealt two cards from a standard deck of cards that one of them will be the ace of spaces. It is a little under the chance that if you are dealt three cards from a standard deck that one them will be the ace of spades.
It is roughly the chance that if you pick three random members of the US House of Representatives that at least two of the three will not be reelected.
If It is about half as likely as the chance that a given US soldier in Iraq over the last decade will have been killed or too badly injured to return to duty (generally estimated to be around 9%). ETA: This number is wildly off. Disregard.
It is slightly less likely than your expectation for Schrodinger's cat to be alive if you run the experiment 5 times.
It is a bit under the chance that if you put your money on two numbers on a roulette wheel that one of them will turn up.
It is slightly over the chance that if you meet two random South Koreans that their last names will both be "Kim".
ETA: Here's a depressing one: It is around the chance that if you pick two children with childhood leukemia that they will both survive five years.
Who exactly?
--Le Feu (Under Fire), translation.
Oh. Hmm. I don't remember where I saw this but that number is my background fact set. But when I look at the actual numbers this is clearly false. There have been around 30,000 people wounded or killed. (Source) and around a million who have served. That means that the probability of being wounded or killed at all is around .03, which is much smaller, and that's even before the fact that I said wounded severely enough that one can't keep fighting. Also in retrospect my number was obviously too high. Severe failure of rationality on my part. Ugh.
I thought that number was highly suspicious, but I attributed it to the combined category (killed or too injured to return -- which of course are very different things from the perspective of the individual concerned!).
It's somewhere between the chance of flipping 4 successive heads and the chance of flipping 5 successive heads with a fair coin.
I was going to respond for I thought I knew many such things, but the few that did not involve rolling d20s involved rolling d%.
My guess would be more that 1 in 20 wrong for a 95% confidence.