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Goldman Sachs model to predict World Cup game results didn’t come close

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Re: Goldman Sachs model to predict World Cup game results didn’t come close

#131

Earlier quoted context omitted.

The point of the model is absolutely not to reduce uncertainty, it is to quantify it, which are two very different things. No model reduces uncertainty in a probabilistic sense. And no, you don’t need statistics or machine learning to say “there is a lot of uncertainty”, but you do in order to quantify that uncertainty.

Say I have two models - model A returns around 20% likelihood that the top team wins the world cup, and model B returns around 80% likelihood. I use both of the modeling techniques a few thousand times in various parallel universes, and both of them are exactly right - 20% of 20% predictions result in a win, and so on. Despite them both quantifying uncertainty accurately, isn't model B still better?

No, because if the underlying phenomenon happened 20% of the time, that’s what you want your model to predict. The point of the model is to describe reality as accurately as possible. So a model that predicts a particular outcome to happen 80% of the time, and the outcome actually does happen 80% of the time, isn’t any better or worse than a model that predicts an outcome to happen 20% of the time that happens 20% of the time.

Re: Goldman Sachs model to predict World Cup game results didn’t come close

#132
post #96

Earlier quoted context omitted.

Urgh, I hate that you can't edit HN comments. First two were just me making a mistake because I write that in manually. That last column makes no sense. It was supposed to be the probability that the model gave to the outcome that occurred, but I got the maths wrong.

There's an edit window of a couple hours, which has probably just past. We've opened it up again so you can go ahead and edit.

Brilliant, thank you very much. Although it might be a tad late now.

Re: Goldman Sachs model to predict World Cup game results didn’t come close

#133

In case anyone was interested here is a table of how likely the model thought each team was to make it through any particular stage[0] along with the stage that that team went out in and the probability that the model gave for that particular outcome (i.e. [probability of making it through the final stage they made it through] - [probability of making it through the stage they went out in]). Groups Round_16 Quarters…

Great work :)

So all in all, the only teams for which the prediction was more than 1/2 were teams out in groups. That is a little underwhelming.

Ah, for Croatia, I believe, it should read 1.5%.

Re: Goldman Sachs model to predict World Cup game results didn’t come close

#134
post #92
post #67

Earlier quoted context omitted.

So this is something that people don't seem to grok quite well, and it really depends on the type of statistical analysis used. Say you make the assumption that the quantity being estimated is truly fixed: that there's some true value for the force of gravity or some true value for the number of people that vote for X or Y. The second assumption that comes along is that the stochasticity observed comes from your pers…

If you expect to get it right (in this particular prediction, Clinton to win) with 95% probability, what does it mean to say that this 95% is with low confidence or with high confidence?

The way I see it (as someone who knows nothing about statistics), confidence would be the difference between 9/10 vs 900/1000. And/or how much effort you spend ramming a square peg in a round hole to have a prediction model.

You have a lot of data about donkeys vs elephants. But this contest is between a mule and a mammoth. If you assume a mule is equivalent to a donkey and a mammoth is equivalent to an elephant, the mule has 95% odds in its favor. But you recognize the assumptions so your prediction doesn't have a high confidence.

Re: Goldman Sachs model to predict World Cup game results didn’t come close

#135
post #89

Earlier quoted context omitted.

The problem is that the 2018 World Cup is not a repeatable event. Neither are most open-market trades (presumably the point of this whole PR stunt being to show that their quants are good at making smart bets in the markets) but they're a LOT closer. Soccer is a pretty data-poor environment, or at least was historically. Before movement trackers, there was very little data to play with. With movement tracking data sl…

wasn't leicester city a "moneyball" team? a zero-to-hero club with a roster of modest salaried players who have statistical synergy? i don't follow much premier league but from what i remember hearing about it, they bucked a trend of spending tens/hundreds of millions for megastars to solo carry the team

There are many premier league teams doing a lot more than Leicester when it comes to statistical analysis.

They did indeed win the league with a budget far below many of the normal contenders, but it was a mixture of good management, luck, a few players having the breakout seasons of their careers which took them to the point where only big teams can now afford them, and a few other players having great runs of form that saw them playing better than they would before or after.

Despite the elements of luck, it was an incredible achievement. But the following season they were back to being a team with no realistic chance of competing for the title, and were actually in a relegation fight to stay in the top division.

Re: Goldman Sachs model to predict World Cup game results didn’t come close

#136
post #95

This article didn't compare the Goldman Sachs model to any other models-- why not compare it with sports betting odds? Would Goldman have made or lost money betting their model was better than the crowd?

Or compare it with the fivethirtyeight blog predictions.
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