Saturday, November 04, 2006

Elimination Speculation - Calculating Fair Odds;

Earlier in the week, we took a look at how the polls have been performing with regards to helping us predict which act will leave the X Factor each week. The only sensible conclusions we could reach were:

Category 1
Acts that have up to 10.6% core support in the polls and sing badly on the night can find themselves in the bottom 2.

Category 2
Acts whose core support is ranked at 7th or below (or lets say "bottom quartile" as the numbers dwindle) can find themselves in the bottom 2 even if they sing well on the night

Bearing these facts in mind, let's take a look at the current polling landscape:

Looking at the poll of polls, we find The MacDonald Brothers toward the bottom of the table again, albeit with a slightly better showing at The Internet Forum and DigiSpy.

We also see Robert fitting perfectly into a "category 2" act, and given that he has already been beaten by The Macdonald Brothers in a previous show, he is looking vunerable again this evening.

How can we account for the remainder of the acts? In previous weeks acts above 5.6% in the polls tend to need to have a bad song to make it into the bottom two, but that was with a lot more sub 5.6% acts in the competition.

The bottom line is that we can't be sure that Nikitta, Ray, and Ashley are safe. We can make the assumption that Ben, Leona and Eton Road are safe however, without stretching the bounds of reason.

This leaves us with five acts, and hence ten possible bottom two pairings. Let's assume that each of these pairings is equally likely to be the bottom two (i.e. 10% chance). We can then say, assuming that each pairing turns out to be the bottom two, who is likely to survive? This is where we can factor in information such as The Macdonald Brothers almost certainly being beaten by all four of the other acts should they make the bottom two. Other pairings are harder to call, and hence are 50/50, but here is a screenshot from a model we have been developing that can help us to quantify our views. The opinions represented in the left-hand column are Statman's own .

As you can see, I have allocated a 5% probability that the MacDonald Brothers will survive against any other act should they wind up in the bottom two this evening. Other pairings can also be seen, and you can see for example that in the scenario Nikitta vs Ashley, I have allocated a 20% probability that Nikkita would survive. The right hand column shows that I have allocated an equal probability of 10% that each pairing does actually turn out to be the bottom two.

Using these assumptions, the model tells us the following:

The result above is only important to me because I believe my input probabilities are sensible, and as such I can use these results to find value in the betting exchanges according to my assumptions.

If you don't believe my probabilities are reasonable, then please feel free to suggest alternatives, because I understand that each gambler will have different subjective inputs.
The model was devised to be a tool to help readers find value, rather than display a set of odds that I personally think is superior, so please feel free to send your probabilities to me.



Wednesday, November 01, 2006

Trying To Get A Peak Under The Kilt

Here at Special Bets we understand how relying purely on polling data to make betting decisions can be dangerous. There can be, and often are, factors that most polls simply do not capture, and it is at your peril that they are to be ignored.

A perfect example of this kind of behaviour is the market’s current addiction to making The MacDonald Brothers hot favourites to go as soon as the weekly elimination markets open. For three consecutive weeks, and four eliminations, the boys from Ayr have had the shortest odds to get the chop, and yet still they are still happily crooning away. If you had blindly followed the polls this series you would be in a world of pain right now.

Let’s take a look at where the polls have been lacking. The table below shows the Macdonald Brother’s poll of polls ranking, alongside the equivalent data for the contestants that actually formed the bottom acts each week:

Given the judges comments so far this series, we can be almost certain that as soon as The Brothers are forced to sing for survival they will be eliminated before you can say “do you want fries with that?” However, they are benefiting from a base of support that is not showing up in the polls, most likely coming from their status as “The Scottish Act”.

The key question is – how long can this go on for? Unless you think these guys are coming top in the voting each week, and that they will win the whole thing, we have to put some thought into at what point the competition will become too fierce for the boys to rely on the tartan voter.

The table above gives us a couple hints, namely:

1.) Acts that have up to 10.6% support in the polls and sing badly on the night can fall below the tartan vote.
2.) Acts ranked 7th or below can be beaten by the tartan vote, even if they sing well on the night

Are the MacDonald brothers running out of fellow contestants that fit the description above? Certainly, there are four less of them now than there were at the start of the series…

We will update the Poll of Polls later this week and let you know our thoughts



Tuesday, October 31, 2006

X Factor - Our Latest Poll Update - Leona makes a move;

We're publishing the final results of our latest X Factor Poll today which was taken 28/10 - 30/10. Leona Lewis is the "story" this week. You are quite a fickle lot and Leona's performance of Summertime has had you dropping your allegiances to all other contestants apart from Ben like so many hot bricks.

After excluding those who did not watch Saturday's show from the the responding group of 849 you told us Leona, Ben and Ray were your favourite performances on Saturday night;

Overall, Ben remains your favourite contestant but as you can see in the bar chart below, Leona has made up a lot of ground. Eton Road clearly have supporters despite poor performance perception and make it into 3rd place;

Below, last week's "overall favourite" question. Leona +12% over last week, Ben -4%, Eton Road -6%;


Leona's Saturday performance has been reflected quickly in the odds; but for now, we're not tempted to back her at current levels. Leona's performances before last week were quite poor in our opinion. For Leona to win this show she will need to be consistent - which is made more difficult by the show's obsession with "themes". Leona Lewis singing ABBA should be quite a challenge...