RE: Observation selection effects

`Eric Cavalcanti writes:`

```From another perspective, I have just arrived at the
road and there was no particular reason for me to
initially choose lane A or lane B, so that I could just
as well have started on the faster lane, and changing
would be undesirable. From this perspective, there
is no gain in changing lanes, on average.
```

Here is another example which makes this point. You arrive before two adjacent closed doors, A and B. You know that behind one door is a room containing 1000 people, while behind the other door is a room containing only 10 people, but you don't know which door is which. You toss a coin to decide which door you will open (heads=A, tails=B), and then enter into the corresponding room. The room is dark, so you don't know which room you are now in until you turn on the light. At the point just before the light goes on, do you have any reason to think you are more likely to be in one room rather than the other? By analogy with the Bostrom traffic lane example you could argue that, in the absence of any empirical data, you are much more likely to now be a member of the large population than the small population. However, this cannot be right, because you tossed a coin, and you are thus equally likely to find yourself in either room when the light goes on.

`--Stathis Papaioannou`

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