Doping in sport is considered one of the most egregious things an athlete can do — and when it occurs at the Olympics it is all the more shocking. The London Games are being held up to be the “cleanest” and most-tested Games in history — but does this mean there aren’t drug cheats?

Former track and field star Marion Jones, who won five gold medals at the Sydney Games, never failed a drugs test. On October 5, 2007, Jones admitted to lying to federal agents about her use of steroids before the 2000 Olympics and pleaded guilty at the US District Court for the Southern District of New York.

So just how many drug cheats might there be at the Games?

The simple answer is we really have no idea. Estimates range from the “official” answer of 2% right up to 35% depending on the approach of the research.

The World-Anti Doping Agency (WADA) and the national equivalents (ASADA here) carry out drug testing on elite athletes and have consistently detected a prevalence rate of about 2% over the past decade. Based on WADA’s own statistics, that means at least 200 (of the 10,000 or so) athletes in London are doping.

They won’t catch all of them as only every medal winner, and half of all participants will be tested, taking the likely number caught to about 100. If we remove the dozen already sent home, then across the next two weeks we should have at least 90 cases of confirmed doping.

To put the numbers into historical perspective, tests caught 11 (0.47%) in Sydney, 26 (0.74%) in Athens and 20 (0.42%) in Beijing (including six horses). All these figures are considerably below the long-term average of 2% and below the 100 cases we should see in London (the total number of athletes was 10,000-11,000 in each Games).

The reality of the situation is that no one actually knows how many athletes dope and get away with it.

WADA’s figure only represents those who got caught. Current research, using a variety of techniques, has estimates ranging from 5% to 35% of athletes doping. A study of the blood profiles of track athletes collected since 2001 showed that 14% engaged in blood doping — but with a clear variation based on the runner’s nationality, perhaps indicating a return to the dark days of systemic doping like in East Germany during the 1970s and ’80s.

When athletes are asked how many other athletes are using, they guess about 10%. A recent German study showed that actual doping rates were eight times the testing rate, so in the case of WADA’s 2% one could assume a rate of 16% of athletes doping.

Athletes get away with doping using a variety of means. They use drugs that are undetectable (“the clear” in Jones’ case). They modify their doping and training regimens to only use when least likely to be tested. They only take enough of a substance to stay below the critical test thresholds. They cheat the tests — through a variety of means. There is also the implication that doping may be organised by some governments.

It is important to remember, however, that the outcry and zealous response to doping in sport is out of all proportion to the actual effect it has on performance. You will never be an elite athlete because you had the best drugs — what they do is make an athlete a little bit better, which in the context of the 100-metre sprint may be the difference between a gold medal and placing.

The real differences in athletic performance come from the wealth differences among countries. Ask yourself why we rarely see Third-World athletes in highly technical or equipment-expensive sports. If your country has the money you can have the medals. Nutrition, equipment, facilities and paid time to train are all far more important and effective than drugs.

Nonetheless, doping is central to sport arguments about “a level playing field” and drugs will remain an issue at the Olympics. A perusal of the statistics shows though that the athletes likely to get caught in London will be the “unlucky” ones — plenty must be getting away with it.