Ratings to prices

[m_v2040]

Hi guys,

I know this has pretty much been covered before but the methods dont really fit my ratings so i need a little help....

Lest say i have a 2 horse race.

Horse a is rated 100
Horse b is rated 90

Now ordinarily you COULD say horse A is $1.90 and horse B $2.10 to a 100% market. But my problem is that in my mind and from experience i would expect horse A to be around $1.45 and horse B around $3.25.

Has anyone got any suggestions for instance you were to convert TAB ratings to a market?

Cheers.

[Bhagwan]

Ozracetools has a program that can convert pts to prices but its all relavent to field size.

Cheers.

[crash]

Backing either would require a very high SR [especially A of course].

Often, neither will win.

[goty0405]

I think it really depends on the ratings and how they are defined. In your example you're talking about a 2 horse race. If you think about any sporting match, when 2 teams playing are closely matched (e.g within 10% of each other, which is what those ratings say) then having prices of $1.90 and $2.10 is actually quite likely.

[m_v2040]

Guys,

Thanks for replies.

I think the question was a bit misunderstood. I quite understand how to convert ratings to prices, hence the example below. And in a 2 horse field i wouldnt say often neither would win :)

The point im trying to make is, in my ratings there isnt only a 10% difference in the 2 horses, by my ratings it is quite larger than that. I have found a formula for what i was trying to achieve so i will give that a go.

Its pasted from another forum, hopefully that is ok...

Q. "Is it possible to create an Excel spreadsheet to calculate odds or probabilities from ratings.

Say for instance I have a 6 horse race with the following ratings:

Horse A 161
Horse B 158
Horse C 150
Horse D 146
Horse E 140
Horse F 139

Is there a way I can enter the ratings and excel gives me the odds or probability of winning?"

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A. There is a crude way of doing this. It has a few problems which can easily be overcome but the maths becomes more complex.

All you need to do is to calculate each horses 'percentage of the total ratings'.

Horse A 161
Horse B 158
Horse C 150
Horse D 146
Horse E 140
Horse F 139

Using Excel put 161 in A1, 158 in A2 etc.

In A10 enter

=sum(A1:A6) (answer here should be 894)

In B1 enter

=A1/$A$10 (answer should be 0.180089

Copy this formula in B1 down to B6

What you have now is the percentage of the total each runner has. So in theory Horse A has "18% of the ratings", Horse F 15.5% of the ratings etc.

To convert probaility to odds you just need the formual odds = (1 / prob) -1

In C1 enter

=(1/B1) - 1 (answer should be 4.552795)

Copy this down for all runners

There you go. That's your betting forecast..... Your top rated is roughly a 9/2 chance and your 'outsider' is roughly 11/2

Not very exciting is it. The reason for this is because your ratings are too tight at the top - they all tend to be around 140-160 and this is a narrow range.

What you need to do is to re-range the figures into something which spreads it out a bit more e.g. range from 1 to 10, or 20 to 100. Here I will show how to range from 10-50 so that the minimum rating is 10, and the maximum is 50.

First find the minimum and maximum ratings. As you have done this in numeric order they are A6 and A1

in A11 enter

=A6

in A12 enter

=A1

in A13 enter

=A13-A12 (should be 22)

Now we have the min, max, and range of all the ratings 139, 161 and 22

In E1 enter

= (10 + (40 * ((A1 - $A$11) / $A$13))) answer should be 100
Copy this down to E6 and you should see:

50
44.54545
30
27.72727
11.81818
10

These are now the new ranged figures. All you have to do is to calculate each percentage share of the total again and convert to odds like in the first bit. Here's the final figures:

Horse A 2.38/1 (5/2)
Horse B 2.8/1 (11/4)
Horse C 4.6/1 (9/2)
Horse D 6.4/1 (13/2)
Horse E 13.3/1 (14/1)
Horse F 15.9/1 (16/1)