Reference: http://en.wikipedia.org/wiki/Poisson_distribution

In regards to the Poisson probability function in Excel which is for example
=POISSON( 1.5, 1.5, FALSE )
will show 33% if formatted to percent.

Does this formula conclude,or give further weight to the common rule of thumb that favorites win 33% of the time ?

One can play around with the 1.5, 1.5 and obtain some interesting figures.

My other question is, out of the 1.5,1.5 entry, which of the 2 is the bookie and the punter, the left or the right?

I was also thinking, if my assessed odds are 1.5 and the bookie is 1.5 ironically as well,
does this mean the formula is saying there is a 33% chance winning?

Other examples
=POISSON( 2.5, 1.5, FALSE ) = 25%
=POISSON( 1.5, 2.5, FALSE ) = 21%

Can someone explain this is plain English please.

Thanks