2022 Grand Nash overrround

“A simple thread from a simple bloke” – IMO it’s neither, btw, it’s actually an excellent thread from an excellent contributor to an excellent forum and I just love topics like this.

Ginger would find value if they went 300%

“What overround do TRFers believe would be fair?”

Cracking question IMO and in defence of bookmakers the true over-round is at the odds at which bets are actually laid, not those on display at any given time.

A horse could be 12/1 having been laid at 16s and so on.

That said, a lot of Grand National bets are still struck at SP.

1%-1.5% (140%-160%) a runner might once have been considered fair, but there’s been a dirty great big betting exchange around these past 20 years and the current margin win only there is 101.2% (less 2% commission) and it’s 11/1 the field.

That’s the bar nowadays.

Definitely – but bookmakers invented each-way terms which clearly suit them.

Plus you don’t want to make it complicated for recreational punters who I doubt would be keen on the place only odds on offer.

First figure the odds to 100% book, second figure percentage chance which all add up to 100%, name of horse, marks out of 5 for acting on good ground, marks for trainer in form. What my 100% book + a bookies mark up would be (as odds), what the odds are as percentages, last figure is each percentage gradually added up so the total is 140.3%.

17/2 10.5% Delta Work 4….// (7/1) 12.5
9/1 10% Any Second Now 3…./*? (15/2) 11.7…. 24.2
10/1 9% Enjoy D’Allen 5….//? (17/2) 10.5….34.7
11/1 8.25% Snow Leopardess 2….* (9/1) 10….44.7
18/1 5.25% Fiddlerontheroof 5…./* (14/1) 6.7….51.4
20/1 4.75% Run Wild Fred 5….// (16/1) 5.9….57.3
22/1 4.25% Eclair Surf 2….// (16/1) 5.9….63.2
22/1 4.25% Minella Times 3…./ (16/1) 5.9….69.1
25/1 4% Escaria Ten 3….// (18/1) 5.3….74.4
25/1 3.75% Death Duty 5….// (20/1) 4.8….79.2
28/1 3.5% Longhouse Poet 1….? (22/1) 4.3….83.5
28/1 3.5% Fortesque 3…./ (20/1) 4.8….88.3
28/1 3.5% Burrows Saint 5….* (22/1) 4.3….92.6
33/1 3% Commodore 3….-/ (22/1) 4.3….96.9
33/1 3% Mighty Thunder 5….** (22/1) 4.3….101.2
40/1 2.25% School Boy Hours 4….* (25/1) 3.8….105
50/1 2% Cloth Cap 5…./* (33/1) 2.9….107.9
50/1 2% Two For Gold 3….// (28/1) 3.4….111.3
50/1 2% Santini 5….*? (33/1) 2.9….114.2
66/1 1.5% Freewheelin Dylan 5…./ (40/1) 2.4….116.6
66/1 1.5% Dingo Dollar 5…./ (40/1) 2.4….119
100/1 1% Deise Aba 2….// (50/1) 2….121
100/1 1% Kildesat 5X…./* (50/1) 2….123
100/1 1% Lostintranslation 5…./* (50/1) 2….125
100/1 1% De Rasher Counter 2….// (50/1) 2….127
125/1 0.8% Mount Ida 2….// (66/1) 1.5….128.5
300/1 0.3% Augusta Gold 1….* (80/1) 1.25….129.75
300/1 0.3% Bahama Bull 4….* (80/1) 1.25….131
300/1 0.3% Anibale Fly 3….// (80/1) 1.25….132.25
300/1 0.3% Discorama 2….-/ (80/1) 1.25….133.5
400/1 0.25% Samcro 3X….// (100/1) 1….134.5
400/1 0.25% Noble Yeats 2….//? (100/1)….135.5
400/1 0.25% Blaklion 5X….// (100/1) 1….136.5
500/1 0.2% Coko Beach 2….// (125/1) 0.8….137.3
500/1 0.2% Romain De Senam 5….** (150/1) 0.7….138
500/1 0.2% Domaine De L’Isle 5X…./*? (150/1 0.7….138.7
500/1 0.2% Poker Party 5X…./ (150/1) 0.7….139.4
1000/1 0.1% Top Ville Ben 0….-/ (200/1) 0.5….139.9
1000/1 0.1% Class Conti 1….* (250/1) 0.4….140.3

So imo a fair overround would be 140%.

Liverpool on course bookmakers

“GT why is an OR of 140% fair? Why should more runners equate to more profit? Genuinely interested as you have clearly done some mathematics on the topic”.

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Apologies for anything thought patronising in the following TTC, this is also for those looking in with less knowledge:

In order for bookmakers to be fairly sure of making an overall profit they need a mark up for every horse when making a book. Therefore the more horses in a race the more overround is needed. Each horse does not get the same mark up. Shorter prices tend to have more mark up, ie in another race if thinking a horse has a 20% chance (fair 4/1) then the next price up is 7/2 which is 22.2%. So the least mark up a bookie is able to do on a 20% chance is 22.2 – 20 = 2.2%… And the more difficult a horse is to work out, the larger the mark up has to be in order to be fairly sure of getting that horse right… Which is also the reason maiden and novice races where little is known tend to have more mark up and more overround. But even in the National there are some whose chance is difficult to way up. Some are improving and some that may return to previously better form, so need a larger mark up.

eg If looking at my list, Delta Work I make a 10.5% chance today which equates to fair odds of 17/2.
Adding a 2% bookies mark up makes him 10.5 + 2 = 12.5% and 12.5% = odds offered of 7/1. Delta Work has a great chance on his x-country form but will he show his best if surrounded by a large field? X-Country was heavy where as this is good. Does have excellent good ground form but that’s a long way back in his form… and has he had an injury since and no longer as effective on good? Has he recovered from Cheltenham? There are enough questions for Delta Work to need a larger mark up.

My idea of Top Ville Ben’s chance on good ground is only 0.1% which equates to a fair 1000/1 and so I’d only add 0.4%, so 0.1 + 0.4 = 0.5% which equals 200/1 offered. Top Ville Ben’s amount of ability is well established and is pretty much certain to need softer than it is today. So his chance is small and not many question marks.

Bookmakers probably calculate how much overround is needed for the whole race and then keep that figure in mind as they change the market when more money for some than others and prices change.