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Old 21st July 2004, 02:55 PM
jakelee jakelee is offline
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Join Date: Jan 1970
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Hope you don't mind me fielding this one moeee - please correct me if I'm off the mark.

From my understand of the relationship between spread and odds, you need to look at three cases.

CASE 1: Home team cannot lose
CASE 2: Both teams are equal
CASE 3: Away team cannot lose

note: ? = infinity if it doesn't show up.

For Case 1, the start for the Home team would be -∞ (infinity), and for the away team +∞ (infinity). The odds for the home team would be $1.00, and the away team $∞ (inf).

For Case 2, the start for both homa and away would be zero. And in a 0% vig bookie, the odds would be $2.00 on each team, or $1.85 on each team at the TAB.

For Case 3, it is the revese of Case 1. +∞ for Home and -∞ for away. With $∞ for home and $1.00 for away.

OK, so what type of equation would best fit this data? Next, I got a whole load of sample odds and starts from the TAB, and plotted start vs. odds. (I've lost this since, but I could do it again with a season's worth of data).

The curve that fitted the data most closely was a TAN curve. There is an example here: Sample Tan chart

Now, just look at the middle curve. And imagine that along the x-axis we have the odds. With 90^ being $1.00 for the home team, and 180^ being $2.00 for the home team or the away team. Then 270^ again being $1.00 for the away team. Like this:

x-axis |--------------+--------------|
HOME $1.00 $2.00 $∞
AWAY $∞ $2.00 $1.00
90^ 180^ 270^

Now, let's take a look at the y-axis. Assume that this represents the start for the home team. Also, pretend that it is soccer (you just change the scale for different sports).

So zero on the y-axis represents a start of zero for the home team, and thus a start of zero for the away team. And from the lookup, you can see that the correct odds should be $2.00 for home, and $2.00 for away.

Let's look now at a start of -2 for the home team. This equals odds of about $1.20 for the home team. You can then work out the odds for the away team based on the bookies vig.

What you can see is that as the start for the home gets closer to -∞, the home team odds approches $1.00. And as the home team start approaches +∞, the home team odds approach $∞ .

When I did this years ago, I found that there were points in the graph where you got better odds staking on the win rather than the start in a few places (only for the fav.). It has something to do with the start only moving in 1 point steps, while the odds could move in smaller fractions.

I am sure I can do it again if someone could point me to a spot where I can find the start and the odds for about 1 season's worth. I could build a spreadsheet that will show you the correct odds based on the start.

Hope that helps.

JL.



[ This Message was edited by: jakelee on 2004-07-21 14:56 ]
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