I got an idea from a previous post to try to get a rough number of self-identifying zoophiles throughout the world. I make no claim to the overall validity of these numbers, but assuming they are valid, this calculation should give a good estimate of those numbers. My source for this is the 2012 Furry Survey and the Battlecrops zoo survey.
The idea behind Bayesian analysis is that by taking conditional probabilities and viewing them in two different ways, we can get estimates for unknown probabilities. The basis for this is the following equation:
Probability of B * Probability of A given B = Probability of A & B = Probability of A * Probability of B given A
In short hand, this is
P(B)P(A|B) = P(A&B) = P(A)P(B|A)
In words, to be a member of two groups, you have to be a member of one group and then, given that, be a member of the other. The order of the groups doesn't actually matter for the numbers, so we can connect the left and the right side. Specifically,
P(Zoo) * P(Furry|Zoo) = P(Zoo & Furry) = P(Furry) * P(Zoo|Furry).
Since we want the probability of being a zoo, we modify the equation on both sides to
P(Zoo) = P(Furry)*P(Zoo|Furry)/P(Furry|Zoo).
If we fill in the three probabilities on the right, we can get the one on the left. P(Furry) is the hardest one to estimate, but from the comments on the bottom of this page, we might get a more reliable estimate than in the post itself. Specifically, Mark's comment estimates that there are 167,000 unique FurAffinity members, and Patrick Drabax's comment reports that 63% of furries use FurAffinity. So we get 167,000/63% = 265,000 furries on Earth. Given that there are about 7 billion people on Earth, this means
P(Furry) = 265,000/7,000,000,000 = 0.0038%
The other two are more straightforward. We get: P(Zoo|Furry) = 4015/28832 = 13.9255% P(Furry|Zoo) = 148/375 = 35.7%
So, putting it all together, we get:
P(Zoo) = 0.00379%*13.9%/35.7% = 0.00148%
If we take the world population and assume this is correct, we get
7,000,000,000 * 0.00148% = 100,000
This means that we number more than the population of a small city.
I think this estimate is actually a little low, given the Internet-centric nature of the surveys involved, but it's pretty staggering.
Edit: I screwed up one of the supporting calculations, so my number was way too high. But it's a lowball estimate anyway.
Yay probability theory! My favorite part of statistics!
Interesting numbers. I get the feeling that most non-zoos have no idea that there are that many.
The trouble is that we're spread out and very quiet. Few people would realize
I'm surprised to say the least - I thought there were as few as 10,000.
With this estimate, it looks like we have the numbers to start our own country! A place of open-mindedness, a place where all species are treated with dignity and decency, a place where there Zeus (in his swan form) watches over us and protects us from the darkness of the world!
This place, shall be called...
Um... Shoot, I've lost it. Any ideas?
Zootopia
Off topic but I want to see that movie when it comes out: http://www.imdb.com/title/tt2948356/
Not off topic, this was the reference I was making! :P
I see what you did thar
You clearly messed up somewhere seeing as there being 10,000,000 zoophiles 37.5% of which are furries implies there are more furry zoophiles than there are furries period.
It seems like you forgot that the result here
Which is actually 0.00148% is already a percentage figure and doesn't need to be multiplied by 100, which would give the erroneous result of 0.148%.
So the correct calculation and result here is 7,000,000,000 * (0.00148)/100 = 100,000
This is consistent (rounding errors aside) with a simpler way of doing the same kind of analysis:
If 14% of 265,000 furries are zoophiles, then 265,000 x 0.14 = 37,000 furries are zoophiles and vise versa.
If 37,000 zoophiles are furries, and 37.5% of zoophiles are furries; then there are 37,000/0.375 = 98,000 zoophiles.
Thanks for pointing this out. It's a little embarrassing, but I was in a rush at the initial posting and didn't notice. Glad to know there are others here who understand math.
Also, our methods are equivalent here. It's just better explained in words.
No worries, cool ideas!
I do think there might be some methodological issues and sample bias effecting the sample populations. It would be interesting to see the same analysis using Kinsey's data to get population estimates.
I think there are easier ways to go about this. There are surveys (such as Kinsey's), that do not ask about self-identified zoophilia, but about things like sexual experiences with animals, or about sexual fantasies involving animals. They show much higher numbers, and I keep thinking that the truth is somewhere inbetween those estimates and yours.
When it comes to Bayesian statistics, I'll ask my bf who knows about that stuff, I'm not very familiar with that method.
Cool post. One thing I thought of is maybe not use the population of the earth. Im guessing the majority of people using those sites are going to be from europe/NA/Australia. Using my google-fu I came up with these numbers
europe - 742.5 mil
North america - 528.7 mil
Australia - 23.13 mil ( - interesting, I didnt realise the population was that low.)
total of those 3 countries = 1.29 billion
using this number, P(Furry) = 265,000/1,290,000,000 = 0.02%
I'd do the rest but I suck at stats so would mess it up but you get the point. This number sounds a lot more realistic IMO. Unless Im completely off the mark and the majority of china and india use furaffinity as well, but I doubt it.
You're assuming that P(Furry) is equal amongst all populations when you divide by 7e9. P(Furry, USA) isn't necessarily equal to P(Furry, China). Even if it was, I would expect P(FurAffinity user, USA) to be unequal to P(FurAffinity user, China).
Some other surveys show zoo-desires at 2.2% of men and 3% of women
Oh math, there's something kind of soothing about it, the numbers that just fit together and give a concrete provable answer. This is neat, thanks for writing it up for us. I never actually learned probability theory during my education, which is a bummer.
I actually suspect the real number is higher than this estimate for a few reasons, 1) I'm pretty sure there are a LOT more furries in the world than Drabax estimates. FA is pretty localized to the Western world. I see some Eastern users but most of them seem to come from Europe or North America. There's also the multitude of countries that don't have internet, or such an online focused culture, some of us may remember what it was like to be furry in the 80s before the mainstream net. We/they were there, just didn't have an outlet. Then there's the non-first world countries where bestiality may not be such a massive taboo that people can have these feelings and practices and not be ostracized or criminalized.
One more thing has occurred to me recently. The language-style of Reddit overall is atypical, making all of us closer to r/mensa (for example) than to typical Facebook comments. I would expect any survey distributed through Reddit to be biased towards the geekier, higher-IQ end of those spectrums. Geek-ness is associated with furry, but I'd be marginally surprised if there was any association between IQ and zoosexuality. Not sure how that modifies the probabilities (and I have work to get back to rather than spend time on this now) but it feels like it ought to.