The secrecy surrounding sex work is reflected in the poor statistics about people who are involved in it. How many sex workers are there, how many clients and how many facilities? No one knows exactly. Most of the time, people are just guessing. It turns out to be difficult to determine the exact numbers of not only sex workers, but also of sex facilities. The number of clients also remains a mystery. When they came into the picture as the most significant party in the fight against AIDS, researchers presented the shocking figure that one in five men Dutch men is a visitor of sex workers. But later it turned out that in the Netherlands, one in ten men regularly visits prostitutes; and one in five had ever done so somewhere in the past.
All these estimates contain margins of error ranging from thirty to almost seventy-five percent. For example, one regularly hears that the percentage of ‘forced women’ is 50-90%. In quantitative research, an error margin of five percent is usually allowed. But apparently, in prostitution research, the presentation of vague figures is considered more acceptable than in other scholarly work.
The figures presented are always nice round and, above all, large numbers. Numbers are systematically overestimated. This is not something specific for prostitution research, but characterizes every investigation into alleged or actual social abuses. With good intentions, authors try to put the abuse on the political agenda. They assume that large numbers carry more weight than small ones. A number of mechanisms are involved in overestimating the scale of the phenomenon. In the first place, there is sometimes deliberate exaggeration. For example, K. Schaapman and A. Asante (2005) claim that there are 8000-10,000 prostitutes working in Amsterdam. This is based on an old estimate from the Municipal Health Service.
2008: A journalist calls De Rode Draad (Dutch sex workers organization and asks how many sex workers are active in Amsterdam that day. De Rode Draad: ‘We don’t know’. Journalist: ‘You are supposed to know that!’ De Rode Draad: ‘How many journalists are working in Amsterdam today? You probably don’t know that either.’
The physician Groothuyse, who specialized in treating sick sex workers, complained in 1970 about the vagueness of the figures. He cites a government agency that in 1969 estimated the number of prostitutes (in Amsterdam?) at 2000, but casually remarked that it could also be 1000 or 3000.
Researchers and policymakers tend to repeat each other. In countless domestic and foreign publications on prostitution in the Netherlands, the number of 25,000 prostitutes working in Dutch prostitution is mentioned. Are there really 25,000 sex workers in the Netherlands? Has this always been the case? Does that figure never change? Why is it so difficult to estimate the number of sex workers?
At first, this was 30,000. This last figure is an estimate made by Vanwesenbeeck et al. (1989). Ex sex workers, women who had done it very temporarily were included in this number. This means that all former prostitutes, all people who have ever worked in prostitution, even when they had done it a few days are included in this number. Next this figure started to lead a life of its own, as being the number of active sex workers in the Netherlands. Later on, they thought that this was a bit much, and then they reduced the number to 25,000 at random.
Indeed, there are no reliable figures on how many men and women work as sex worker in the Netherlands. Nevertheless, researchers quote the old estimate as being authoritative that there are 25,000 women working in prostitution in the Netherlands every year. This figure is strange because it will never be more or less, even though everyone claims that the market is growing or shrinking. We might conclude that large numbers are more an expression of a discomfort and moral anxiety on the part of the authors than a faithful representation of the empirical reality.
Annual and daily figures
There is also a lot of confusion about what we have called daily and annual figures. Daily figures refer to the number of sex workers working on a certain location (district, city, country) at any given time. Annual figures refer to the number of different individuals who have ever worked at a certain location in a certain year. In our opinion, the daily figures give the most realistic picture of the size of the prostitution market. The daily figure expresses, as it were, the social ‘pressure’ that the prostitution business puts on a certain location. For example, it makes quite a difference whether, in a city like Utrecht, 200 or 2000 women are active in sex work on any given day. The annual figure does not say much about the size of the market for sex work. (…) In the discussion about sex work, however, annual figures are often used as an indication of the size of the prostitution market.
Sietske Altink in cooperation with Hendrik Wagenaar