Re: Geiger (a challenge)

["Bernard G. Cleyet & Nancy Ann Seese" <georgeann@REDSHIFT.COM>]

John Denker wrote:

> At 09:03 AM 7/8/00 -0400, Ludwik Kowalski wrote:
>
> The fallacy of expecting the spacings to be clustered around the mean
> spacing is equivalent to the well-known fallacy that alleges if a family
> already has five daughters and is expecting another child, it must be a boy
> with very high probability, to uphold "the law of averages".
>
> In fact, of course, births are IID to a good approximation.

I don't think so -- five girls in a row would lead me to expect another girl.  Girls result from (among other things such as genetic factors) infrequent intercourse.  Fertilization early in a woman's
fertile period results in boys -- late girls.  That why during war time so many more boys are produced.  Also the later the fertilization attempt (what euphemisms) the less likely the success.  This
is why sl. more boys are also produced in normal times. To move off  the ~ 50/50 probablity, use an acid or alkaline douche prior (obviously ) to intercourse -- acid for girl I remember.


> For related fallacy, see next message.
>
> >  The experiment contradicts such expectations.
>
> I should hope so!
>
> > It is tricky experiment to setup.
>
> There's no reason for it to be tricky.  There's no reason to use a lot of
> software and hardware (including radioactive sources) that most people
> don't have (and might not want) in their classroom.  You could make this
> point to sixth-graders using dice.  How long a run can we have, rolling one
> die, before a six shows up?  What does the histogram of run-lengths look like?
>
> Warning:  To get good statistics you'd need hundreds of runs, which means
> thousands of dice-rolls.  If you can provide one die per student, you can
> parallelize the data collection.

what do you mean by good -- I using a counting rate of 41 cpm counting for 124 cm -- 1/2 S. / cm. obtained # </= mean 69% of tot.   (correction of my previous post of >64%)  The appearance of
assymetry is obvious!

> If you like, you can use a computer to roll the dice for you.
>    a) You can do the entire job using nothing but excel.  Hint: if the Data
> Analysis option isn't showing on the Tools menu, use Tools::Add-Ins to load
> the Analysis package.  That's where the histogram tool lives.  (Don't
> expect the chart tool to take raw data and histogram it;  you have to form
> the histogram first, then chart it.)
>    b) OTOH it is probably easier to do (and easier to understand) if you
> write a Basic program to roll the dice and form the histogram;  then print
> out the data and chart it using excel.
>
> Huge hint:  If you have excel on your computer, you don't need to buy a
> Basic programming system.  There's a perfectly fine Basic engine hiding
> inside excel.  For excel version 9 ("excel 2000") it's hiding under
> Tools::Macro::VisualBasicEditor.  It's there in earlier versions but I
> forget where it hides;  use the "help" function and look for the word "module".