Mike Raiford wrote:
> (Not that I plan any more.. but since this is my first stupid 
> probability question. This is sort of in the vein of Andy's classic 
> Random Wonderings post series ...Hey, whatever happened to those, Andrew?)
> 
> So, here it is. Stupid Probability Question #1:
> 
> Suppose you're on a 100 year flood plane. Now ... suppose the last flood 
> was some 76 years ago in that area. Does the probability of a flood 
> increase as your approach 100 years, or does the probability of a flood 
> stay the same?
> 
> -OR- is probability irrelevant due to changing conditions?

The probability is based on historical records, and itself could be off.

If the chances of a flood in any given year are not affected by past 
history of floods--and this is presumed to be the case for things like 
this--then the chances do not increase with the dry spell.

It is the same principle as, for example, a family with eight children, 
all of whom are girls.  The parents might think that they are due for a 
boy, but the probability of the next child being a girl is the same as 
it has been all along.

Regards,
John

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