Google云平台对于2014世界杯半决赛的预测，德国阿根廷胜！

由于本人是个足球迷，前段日子Google利用自己云平台预测世界杯八进四的比赛并取得了75%的正确率的事情让我振动不小。虽然这些年一直听说大数据的预测和看趋势能力如何如何强大，但这次的感受更加震撼，因为世界杯是很多人都在关注并尝试去预测的比赛，Google云平台在这个时候站出来预测比赛无疑很让人充满期待。

当然有件事情必须要讲的是，世界杯从来都是冷门出现在小组赛最多，而进入淘汰赛之后就越来越少，所以Google在八进四才开始预测无疑是件很讨巧的做法。不过不管怎么说，靠大数据预测小概率事件本来就非常难，能预测对大多数非冷门已经非常不容易了。

还有一会巴西对德国的比赛才开始，所以刚刚抓紧时间看了一个Google Cloud Platform的博客发现了他们最新的文章，解释了德法大战没有预测准确的原因，顺便给出了半决赛的预测，会不会准呢，很快就知道了！

我翻译了部分文字，内容如下：

 

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Google对于八进四的预测结果，只有法国对德国的比赛预测错误。

• Brazil vs. Colombia: Brazil (71%)
• France vs. Germany: France (69%)
• Netherlands vs. Costa Rica: Netherlands (68%)
• Argentina vs. Belgium: Argentina (81%)

 

Why did we get Germany - France wrong?

为啥德法大战的预测错了？

World Cup teams are especially difficult to model because they play so few games together. USA coach Jurgen Klinsmann recently told the New York Times that he sees his players about as often as he sees his barber. If data is the lifeblood of a good model, we suffered for want of more information. 

预测世界杯的球队表现时，建模是很难的因为他们之前在一起比赛的机会是很少的。美国队的教练克林斯曼对纽约时报说他见他的球员们的次数不比他见理发师的次数多。对于好的建模来说，数据是至关重要的，我们总是苦于得不到足够的信息。

 
But, we know that in the same environment, others fared better in their predictions (h/t Cortana; their model relies more on what betting markets are saying, whereas ours is an inductive model derived from game-play data). 

但是我们也知道在同样的情况下，还是有很多其它的预测比我们做的要好（比如h/t Cortana 网址是http://mashable.com/2014/07/02/cortana-world-cup/），他们的建模更多的是依赖于赌球市场给出的赔率，而我们的更多的是基于比赛的数据。

So, why did we get Germany - France wrong? In the first four games of the World Cup, France took more shots than Germany, had more shots on target, and their shots were from a more “dangerous location” (that is, closer to the goal). This information complements actual goals to form an ‘expected goals’ statistic in our model. 

那么，为什么对德国和法国的比赛的预测错了呢?那是因为在之前的四场比赛中（3场小组赛+16进8一场），法国队比德国队有更多的射门次数，射正球门（所谓射正球门是指打在门框范围以内的射门）的次数也更多，而且他们的射门来自更有威胁的区域（所谓有威胁区域是指离球门更近的地方）。我们将这些信息在与实际进球数据相配合之后，在我们的模型中得出了“预期进球”这项统计值。

Moreover, in the first four games, Germany allowed their opponents to take more dangerous shots, and thus the expected goal statistic was higher for their opponents. And, it allowed their opponents to pass better in their third of the field. In the Germany-France game, France actually outshot Germany with 13 shots vs. 8 for Germany, and 9 vs. 6 on-target. With a little more luck on their side, they may have pulled ahead.

另外，在前四场比赛中，德国队让对手们拿到了更多的有威胁射门，这导致德国队的“预期进球”数值低于它的对手们。另外，德国队让它的对手们在自己的三分之一场地内得到了更好的传球机会（也就是说防守不够严密）。在德国对法国的那场比赛里，法国队其实有13脚射门，而德国队有8脚，而打在门框内的次数是法国队9次，德国队6次。如果不是德国队的运气更好一些，法国队也许早就领先了。

What about the semi-finals?

那么，半决赛的预测呢？
Here’s our predictions for the next round:
预测如下

• Brazil vs. Germany: Germany (59%)
• 巴西 vs 德国： 德国胜率59%
• Netherlands vs. Argentina: Argentina (61%)
• 荷兰 vs 阿根廷： 阿根廷胜率 61%