Olympic stats wizard Bill Mallon has quantified the host-nation bounce, showing that the country that last hosted the Olympics can typically expect to win roughly 70% of the medals it won at home.
The genius of this analysis is that it factors out the growth of the Games (particularly winter) by analyzing the medal count in terms of percentage of medals won. So if the Olympics add 30 events for 2018 (don’t worry — it won’t happen), then sure, Russia could match its Sochi record count. But the percentage of available medals won should drop.
When you’re projecting medals event-by-event, like I do, it’s difficult to account for this bounce. For London and Sochi, I’ve tended to break ties by favoring the home athlete. For London, I overreached, predicting 78 medals for Britain. They got 65. For Russia, I undershot, predicting 26 to an actual 33.
Some of the bounce comes from increased interest at home. Athletes on the verge of retirement stick around to compete. Federations get a bit more sponsorship money.
Some comes from home crowds. Some comes from those crowds affecting the judges. (Looking your way, figure skating folks.)
Brazil has revved up for 2016 with its best-ever medal haul in 2012 — 17 medals. They’ve been in double digits for the last five Games, with 15 in Atlanta 1996 and Beijing 2008.
In 2018, South Korea will surely improve on its total of eight from Sochi. Crowds at the 2002 World Cup turned an average soccer team into a world-beater, and they should have no trouble having the same effect on the speedskaters who underperformed this year.
Duresport.com 
Seems like most of the “host nation bounce” has nothing to do with judging or boisterous crowds. Instead, it has to do with government funding and emphasis on performance. Nations know that they will be under enormous pressure to perform at a home Games, and (recently at least) they tend to commit a ton of money and effort to ensure that they peak at the right time.
Canada epitomizes this. Home crowds and judges’ home-cooking couldn’t bring them a single gold medal in 1976 or 1988. But for 2010, they invested real resources – energy, effort, emphasis, and of course cash – into improving performance, and they ended up owning the podium.
It would be very interesting to see if there is still a perceivable “host nation bounce” even after controlling for resources spent in the run-up to the games. I suspect any bounce would not be significant.
Well, 5 golds came courtesy of Victor An and Vic Wild, who weren’t Russian. I think it’s unclear whether either would have been competing for Russia had Russia not been hosting the Olympics this cycle and increasing developmental spending.
The sliding events seemed to be the most effected by home country advantage. My understanding was that the Russian athletes had a lot of exclusive practice time on the track leading up to the game and a private training facility that other teams weren’t allowed to access. Whatever the reason, any threat the Russians had in the luge/skeleton/bobsleigh events was amplified big time.
I don’t think anyone denies that there is a home nation bounce and the factors most commonly cited are: increased funding; top athletes staying on to compete in a home games; home crowd support; and possibly beneficial judging in favour of home athletes in the subjectively judged sports.
Having hosted the 2012 games Great Britain has committed to maintaining funding for the olympic sports at or above the level in the preceding cycle in the run-up to Rio. As a result it should be possible to gain a better idea of the impact on a home nation’s performance in the other three areas. Of Britain’s 65 medals 14 were in sports with an element of subjective scoring – 5 in boxing, 4 in gymnastics, 4 in equestrian (those with a dressage element), 1 in diving. While there have been few accusations of biased judging in gymnastics and equestrian there have been more questionable decisions in boxing and to a lesser degree diving over the years. These are all strong sports for GB, some historically like boxing and some more recent like gymnastics, so it will be interesting to see how they perform in these events in 2016 to see if there is any evidence of a home bias in judging.
I suspect the biggest factors will actually prove to be the advantage of home crowd support which British athletes invariably cited after their successes in 2012 together with the benefit of experienced medal winning athletes staying on to compete in a home games when they might otherwise have retired, eg. Chris Hoy and Ben Ainslie.
I should have perhaps been clearer in stating that funding is the biggest factor as can be seen by the introduction of national lottery funding for sport in the UK after Britain’s disastrous performance in Atlanta in 1996 when they won just 15 medals and only one gold. Since then, and this precedes the awarding of the games to London in 2005, Team GB’s performance has been on an upward curve:-
1996 – 15 medals
2000 – 28
2004 – 30
2008 – 47
2012 – 65
The point I was trying to make in my previous comment was not that funding isn’t critical, but that the maintenance of that funding will enable the other perceived benefits of a home games on performance to be measured potentially more accurately.