After a couple minutes of research, the lowest number I could find for women in CS was from https://web.archive.org/web/20141221112502/http://floss2013.... Without getting into how accurate it is, I'm just taking it as a very conservative estimate that 10% of OSS software programmers are women. So out of 250 submissions, we'd expect about 25 of them to be from women if the sample is unbiased. And the odds of having only one woman would be... not sure if I did this exactly right but something like (0.1 * (0.9 ^ 249) ) * 250 = 10 ^ -10. Kinda looks like the submission process was biased.
The survey you cite that found 10.4% included software and non-software contributions (such as translators, documenters, community managers, etc.), and found that women contributors were much more likely to be the later. Other surveys, such as a 2017 survey of 5500 contributors to GitHub projects, put it at 3% women [1].
None of that is really relevant, though, because we aren't talking about a generic OSS conference. We are talking about a PHP conference. What is the percent of women who are PHP programmers?
Actually, that number would not be all the useful, either. Such surveys are going to find out what percent of various groups use PHP. That would be somewhat useful for estimating what the conference attendees should look like. Conference speakers, on the other hand, should be people are are doing new things with or to PHP. That's going to be a much smaller group than the people who use PHP, and so is likely to have much more skewed demographics compared to the larger PHP user population.
In a Swedish town where I live there is an monthly sauna event. In the beginning they did not know how to advertise it so the first event they called it Sauna Extreme - an adventure, with baths like hot-and-cold and the grill. The second time they called it Wellness with the exact same baths, but with one extra bath with a hair pack.
It was fully booked for men during the first event, but only one woman joined. The second event, fully booked for women and only two men.
Third event they called it Wellness Evening, with no mentioning of any hair pack or grill, and it ended up fully booked for both men and women. Forth event similar.
The probability of those outcomes happening through naturally probability is extremely unlikely. It is almost like people will interpret subtle gender identity in events, and then have it impact their decision to join.
This is absolutely the worst kind of analysis. Find some results we don't like, then work backwards using bogus inputs (that are easily refuted, as tzs did below, or which themselves may have been biased, faulty, outdated, not directly relevant, etc) and arbitrary math to determine, yep, the process was biased! I just proved it! Let's call out these bad people! There's no possibility that I am wrong, it has to be those bad people!
No alternative explanation needed. The objective fact is they received 1 proposal from a woman out of 250. If you want to claim that ratio proves the process must be biased, you need to show some evidence, not a bogus math formula which was flawed from the beginning.
As other repliers have already stated: a) you chose a flawed survey to get your "10%" figure, b) the percentage of "women in open source" is far different, for a variety of reasons, than the percentage of women who are likely to submit a proposal to speak at a PHP conference in Germany, c) you dismiss any possibility that unusual ratios could possibly be due to reasons other than bias (is lung cancer biased because it overwhelmingly affects older people?)
You've offered zero fundamental evidence of bias (i.e. they filtered their mailing lists, they adjusted female speaker ratings, etc), other than the math doesn't work out the way you'd like, which isn't surprising given the invalid inputs and assumptions you started with.
I think we literally mean different things by the word "bias". It doesn't have to be intentional.
Even if somehow the population they were drawing from was 99.6% male, I would not comfortable with conference organizers who just passively accept that. At best, they're still perpetuating other people's discrimination. I think the fact they didn't even care to address that is what made these speakers uncomfortable enough to leave.
Women are less assertive and more risk averse. This conference is not any different from any other conference, the field in the whole or society at large. This particular phenomenon was even highlighted in nature multiple times:
> Kinda looks like the submission process was biased.
While skewed outcomes can make you suspect bias, they simply are not sufficient evidence to conclude that there is bias.
For example, around 50% of the population is male. Yet 0% of all births are to males. Obvious discrimination against male fathers! Silly me, no, of course not bias. There is some other factor at work.
Or take the 100m dash as Olympic discipline, or in fact most of the track and field running events. Extreme racial skew. Bias?
And no, I am not saying that these same factors are at work here, just that you cannot conclude bias from unequal outcomes. In fact, as far as I know the science, it would be exactly matched outcomes that would actually be highly suspect.
See also: Simpson's Paradox ( https://en.wikipedia.org/wiki/Simpson%27s_paradox ). Again, not saying that this is an instance of Simpson's paradox, but definitely saying that just because something looks like bias when superficially examining outcomes, that does not at all mean that bias is the actual cause.
And of course there are a lot of potential reasons why there would be a skew, many of which have been identified as fairly reliable gender differences, including willingness to take risks,
> 10% of OSS software programmers are women
The numbers I found were lower, more in the 1-5% range, skewing toward the lower end: