Odds calculation question.

meriwether

Lads, help needed. My sums are failing me.

I want to sum a number of events together to get the probability og it happening, and calculate fractional odds.

For instance, If Pipe has two runners in a race both quoted at 4/1, I would expect a price for a 'David pipe Trained winner' be 6/4.

I.e. 4/1 is 20% chance (4+1=5/100*1=20% + 4+1=5/100*1=20%)

A 40% shot is 6/4. I dont mean to be patronising, Im laying things out clearly for my own thinking.

The event in question I am talking about is this:
http://http://www.paddypower.com/bet?action=go_type&category=SPECIALS&disp_cat_id=56&ev_class_id=33&ev_type_id=4756&ev_oc_grp_ids=108925&bir_index=

Im looking at FF to get no seats at 40/1.
My logic therefore is that FF to win more than 0 seats is 1/40. I want to test this by adding up the probabilities of FF candidates winning a seat per constituency.

Ireland South: To win:
Crowley 1/10
O'Keefe 11/2.

That means that FF have a 105% chance of winning one, if I add their probabilities together -yes? Is this correct reasoning?

I do this for all the other constituencies.

West: 71% to get a seat
East 93% to get a seat
Dublin 78% to get a seat.

I sum the probablilities together to get that FF have a 374% chance of winning a seat.

How do I convert this to a 'FF to win at least 1 seat' odd, and then invert that to get FF to win no seat?


I fully accept my logic may be flawed above.

Dodge

Bookmakers will say that they aren't independetn events. If FF are struggling to get a seat in Dublin, they're also less likely to get a seat in Leinster

Kinda like the way that the price on a football scorecast is shorter than the combined odds of a first scorer/correct score double would be (if they allowed them)

meriwether

Dodge wrote: »

Bookmakers will say that they aren't independetn events. If FF are struggling to get a seat in Dublin, they're also less likely to get a seat in Leinster

Kinda like the way that the price on a football scorecast is shorter than the combined odds of a first scorer/correct score double would be (if they allowed them)

Id actually dispute that logic. Each constituency is a seperate election. Liam Alyward getting elected or not does not mean that Brian Crowley will het elected, or not.
Sure if FF are at 75% in the polls, they will get elected, but that should be reflected in their price.

A 'FF to win 5 seats and Liam Alyward to win a seat' double is most certainly a related bet however.

Dodge

I'd tend to agree with you but I was trying to look at it from the bookmaker's POV. They're unlikely to let you have any benefit of the doubt

I should point out I'm in work and can't access the PP site so I haven't looked at any of the odds.

ArmaniJeanss

meriwether wrote: »

That means that FF have a 105% chance of winning one, if I add their probabilities together -yes? Is this correct reasoning?

1. Your first step will be to convert this to a 100% book, as obviously FF cannot have a 105% of winning a seat in this constituency. So you'll have to convery by working out the bookies overround (prob around the 25% mark) and distributing it around the odds of all candidates pro-rata.

2. Do the same for each of the other constituencies.

3. Now armed with the actual percentages for each constituency work the Y/N odds for Fianna Fail overall.

4. Revert the odds keeping the book 100% (so if its 88% that Fianna Fail get a seat in constituency W, then its 12% they don't).

5. Work out the odds of the "Don't get a seat" multiplier coming up.

6. Revert this in a 100% book to get the odds on minimum One seat.

7. Wonder afterwards whether it was a bit of a time waste. (P.S, My rough maths doing the above make it about 1/2100 that they get at least one seat).