I know. I was there. That's why I counted only 3 of the 4 events.
> -----Original Message-----
> From: Kelly, Katie [mailto:kkelly@spss.com]
> Sent: Friday, April 05, 2002 11:58
> To: Michael R. Clements; Autocross
> Subject: RE: rain -- again? what's going on?
>
>
> It didn't rain at the Boondoggle.
>
> Katie
>
> -----Original Message-----
> From: Michael R. Clements [mailto:mrclem@telocity.com]
> Sent: Friday, April 05, 2002 11:54 AM
> To: Autocross
> Subject: rain -- again? what's going on?
>
>
> In S.F., the average inches of rainfall for Jan, Feb, Mar are
> 4.4, 3.2 & 3.1. Assuming one day of rain is about 0.4 inches
> on average, that is 11 days, 8 days and 7.75 days of rain in
> these months, historical average. Total average days of rain
> for Jan-Mar is 26.75. Total days is 90.25 (counting Feb as
> 28.25 for leap years). Thus, a rough average probability for
> any given day from Jan to March to have rain in S.F. is about
> 30%. It's a bit lower for Oakland & GGF.
>
> We have had 4 autocrosses so far, in 3 of which it rained.
> The probability to get rain on all three of these days is 0.3
> * 0.3 * 0.3 = 0.027. Thus getting rain on all three of these
> days is only 2.7% likely. And that's if they are all in SF.
> Some were in GGF and Oakland, which get slightly less rain,
> so the probability is actually a bit lower.
>
> Furthermore, now it looks like rain tomorrow morning on the
> school. This further reduces the probability to a number so
> small that it stretches the limits of credulity to imagine
> that it has occurred naturally.
>
> Can anybody explain what is happening? Is there some
> phenomena going on causing it to rain on every event this year?
>
> Michael R. Clements
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