Gold fever: predicting the number of medals for Team GB at London 2012

The great physicist Niels Bohr was responsible for the famous quote “prediction is very difficult, especially if it’s about the future”.  Of course that doesn’t stop us trying – especially when it comes to sport and doubly so if you are hosting the next Olympics in London. Some of my colleagues (Simon Shibli and Chris Gratton) have been making predictions on the number of medals the host nations will get at the Olympics and I thought that I would give it a go too.  As a scientist, I like to amass as much evidence as possible before sticking my finger in the air to make my prediction.

What does history tell us about how many medals we can expect, and what exactly is the ‘host effect’?

Home advantage

According to Shibli and Gratton (and others), it appears that the number of medals a host-country gets before they host the Olympics increases quite dramatically and during their host year, there is an additional home effect.  The bid to host the Games is made 7 years before the event (in our case in Singapore in 2005) – by this point we had already had two decent Olympics under our belts (2000 and 2004) coming 10th in both cases.  By Beijing in 2008 preparations for our own Olympics were well under way. It was our best placing since 1924, with 47 medals and 4th place.

This trend mimics what has happened to other host countries in recent times: Figure 1 below shows what happened to Australia’s medal count before, during and after the Sydney 2000 Olympics: the total medal count and the gold medal count went up, peaking at Sydney 2000 with a drop in Athens 4 years later.  The Great Britain trend is following a similar pattern.

Figure 1. Medals won by Australia and GB between 1988 and 2008.

Market share

Unfortunately, the number of medals available at an Olympics isn’t constant, having gone up from 739 to 958 between 1988 and 2008. You can’t use the number of medals to make future predictions. Any sensible analysis should normalise the data or use what my economics colleagues call ‘market share’. This is calculated by dividing the number of medals won by a country by the total number available. Figure 2 shows both Australia’s and Great Britain’s market share with respect to their host year which has been set to zero.  Australia’s share of the total rose to 6.3% in their host year (2000), dropping back again to about 5.5% four years later in Athens.  It appears that GB is following a similar pattern and is on course to equal the Australians (always a bone of contention with my Australian inlaws).

Here is my first prediction – Team GB will get 6.3% of all medals handed out.  If the number of medals available is the same as in 2008 (i.e. 958), then GB will get around 60.

Figure 2. Share of all medals for Australia and GB with respect to their host year (the host year is set at zero).

Of these medals, how many will be gold? Analysis of all countries at the last 6 Olympic Games shows that, on average, the percentage gold medal share is 1.124 times that of total medal share (Figure 3 below). This points towards GB getting around 7% of the 302 gold medals on offer i.e. about 21.  In Beijing 4th place was 6.3% of golds (GB with 19) while 3rd place was 7.6% (Russia with 23): to get any chance of coming 3rd in London, GB has to get two more golds than last time, and Russia has to do worse.

My foolish prediction

Analysis of what has gone before – especially with Australia – says that we are likely to get 60 medals with 21 of them being gold, putting us 4th in the table.  Now I’m going to ruin all that good work and go with my gut instinct and say that our gold medal share appears to be rising faster than the average – in Beijing we already had over 6% of them and a simple linear fit (Figure 5) predicts that we ought to get around 7.6% of the share of the golds (equivalent to 23).  Perhaps I am also being pulled by the peer pressure of Shibli and Gratton who predict 27 Gold medals.  My modified prediction, therefore, is this:

GB will get 60 medals and 23 of them will be gold.  However, this won’t be enough for 3rd and we’ll come 4th.

So there it is, you can shoot me down now if you wish, but I think you should wait for the final medal table on 12th August.

Steve Haake

Graphs

Figure 3. The relationship between gold medal share and total medal share for the 6 Olympic Games between 1988 and 2008.

Figure 4. The relationship between rank and the share of gold medals for the last 6 Olympic Games between 1988 and 2008.

Figure 5. Share of Gold medals for for all host nations between 1988 and 2008 with respect to their host year (the host year is set at zero). The dotted line is a best fit through the 4 points prior to 2012 and predicts 7.6% of golds.

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About stevehaake

Steve is Professor of Sports Engineering at Sheffield Hallam University. He has a degree in Physics from the University of Leeds and a PhD from Aston University on the mechanics of golf balls on golf greens. He has over 200 publications, including his first book "Advantage Play: Technologies that changed Sporting History" due out in October 2018.

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