Puntz I think you are a bit confused on how to use the POISSON calculation.

I will say I am not a trained statistician but I am self taught and have a better understanding then the average person.

The poisson distribution in excel is as per your post :

=POISSON( X, Y, Z )

X = Value to be tested
Y = Our Predicted Value
Z = cumulative effect (We always want FALSE).

So based on what I read you had a rating of 1.5. When you do this calculation:

=POISSON( 1.5, 1.5, FALSE )

You are basically asking "I came up with a rating of 1.5, what percentage of time is this rating correct ?". In your case it replied that your only going to get your rating correct 33% of the time.

Now you just need to work out how this can be of use in your ratings. Perhaps it would work well to find the range where your rating is likely to be correct. Perhaps its of no use at all.


In regard to your original questions:




Well it adds some weight to the argument if we assume the first number is the publics odds (their guess at the horses chances of winning) and the second is the real chance of the horse then the punters are getting the odds right for a $1.50 chance around 33% of the time. But of course the would get it above and below this number just as often and therefore give rise to the fact that they get the favourite right about 33% of the time.


If depends what your trying to figure out. If your trying to figure out how often the bookie will match your odds then the bookie is first. If your trying to figure out how often your rating will be 1.5 when the bookies is 1.50 then your the first number.


No. Its saying the probability of you getting the same rating as the bookie is 33%. Its not telling you the chance of it winning.

Does that help ?